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TSCHMICiL LIBRARY 
of the 

armed forces 

SPECIAL WEAPOMS PROJEI 
- n - 3 \ 


' Jfehim To * 

SEIK /ffi lECSasS'/ DiSIS 

Limry of Cojiga-^a 








SUMMARY TECHNICAL REPORT 
OE THE 

NATIONAL DEEENSE RESEARCH COMMITTEE 




Manuscript and illustrations for this volume were prepared 
for publication by the Summary Reports Group of the 
Columbia University Division of War Research under con¬ 
tract OEMsr-1131 with the Office of Scientific Research and 
Development. This volume was printed and bound by the 
Columbia University Press. 

Distribution of the Summary Technical Report of NDRC 
has been made by the War and Navy Departments. Inquiries 
concerning the availability and distribution of the Summary 
Technical Report volumes and microfilmed and other refer¬ 
ence material should be addressed to the War Department 
Library, Room lA-522, The Pentagon, Washington 25, D. C., 
or to the Office of Naval Research, Navy Department, Atten¬ 
tion : Reports and Documents Section, Washington 25, D. C. 

Copy No. 

142 


This volume, like the seventy others of the Summary Tech¬ 
nical Report of NDRC, has been written, edited, and printed 
under great pressure. Inevitably there are errors which 
have slipped past Division readers and proofreaders. There 
may be errors of fact not known at time of printing. The 
author has not been able to follow through his writing to 
the final page proof. 

Please report errors to: 

JOINT RESEARCH AND DEVELOPMENT BOARD 
PROGRAMS DIVISION (STR ERRATA) 

WASHINGTON 25, D. C. 

A master errata sheet will be compiled from these reports 
and sent to recipients of the volume. Your help will make 
this book more useful to other readers and will be of great 
value in preparing any revisions. 




VOLUME 


o 

O 


FIRE WARFARE 

INCENDIARIES AND FLAME THROWERS 


OFFICE OF SCIENTIFIC RESEARCH AND D E \ E I. O P M E N T 

\’ A X N E V A R BUSH, DIRECTOR 

NATIONAL DEFENSE RESEARCH COMMITTEE 

I A M E S B . C: O N A X T , C H .V I R M A X 

D I \M S I O N 11 
H . M . C H A I) W ELL. C: H I E F 


WASHINGTON, D. C., 1946 





NATIONAL DEFENSE RESEARCH COMMITTEE 


James B, Conant, Chairman 
Richard C. Tolman, Vice Chairman 
Roger Adams Army Representative’ 

Frank B. Jewett Navy Representative- 

Karl T. Compton Commissioner of Patents" 

Irvin Stewart, Executive Secretary 


^Arniy representative 
Maj. Gen. G. V. Strong 
Maj. Gen. R. C. Moore 
Maj. Gen. C. C. Williams 
Brig. Gen. W. A.Wood, Jr. 

Col. E. A. 


in order of service: 

Col. L. A. Denson 
Col. P. R. Faymonville 
Brig. Gen. E. A. Regnier 
Col. M. M. Irvine 
Routheau 


-Navy representatives in order of service: 

Rear Adm. H. G. Bowen Rear Adm. J. A. Purer 
Capt. Lybrand P. Smith Rear Adm. A. H. Van Keuren 
Commodore H. A. Schade 
^Commissioners of Patents in order of service: 
Conway P. Coe Casper W. Corns 


NOTES ON THE ORGANIZATION OF NDRC 


The duties of the National Defense Research Committee 
were (1) to recommend to the Director of OSRD suit¬ 
able projects and research programs on the instrumen¬ 
talities of warfare, together with contract facilities for 
carrying out these projects and programs, and (2) to 
administer the technical and scientific work of the con¬ 
tracts. More specifically, NDRC functioned by initiating 
research projects on requests from the Army or the 
Navy, or on requests from an allied government trans¬ 
mitted through the Liaison Office of OSRD, or on its own 
considered initiative as a result of the experience of its 
members. Proposals prepared by the Division, Panel, or 
Committee for research contracts for performance of 
the work involved in such projects were first reviewed 
by NDRC, and if approved, recommended to the Director 
of OSRD. Upon approval of a proposal by the Director, 
a contract permitting maximum fiexibility of scientific 
effort was arranged. The business aspects of the con¬ 
tract, including such matters as materials, clearances, 
vouchers, patents, priorities, legal matters, and admin¬ 
istration of patent matters were handled by the Execu¬ 
tive Secretary of OSRD. 

Originally NDRC administered its work through five 
divisions, each headed by one of the NDRC members. 
These were: 

Division A—Armor and Ordnance 
Division B—Bombs, Fuels, Gases, & Chemical Problems 
Division C—Communication and Transportation 
Division D—Detection, Controls, and Instruments 
Division E—Patents and Inventions 


In a reorganization in the fall of 1942, twenty-three 
administrative divisions, panels, or committees were 
created, each with a chief selected on the basis of his 
outstanding work in the particular field. The NDRC 
members then became a reviewing and advisory group to 
the Director of OSRD. The final organization was as 
follows: 

Division 1—Ballistic Research 

Division 2—Effects of Impact and Explosion 

Division 3—Rocket Ordnance 

Division 4—Ordnance Accessories 

Division 5—New Missiles 

Division 6—Sub-Surface Warfare 

Division 7—Fire Control 

Division 8—Explosives 

Division 9—Chemistry 

Division 10—Absorbents and Aerosols 

Division 11—Chemical Engineering 

Division 12—Transportation 

Division 13—Electrical Communication 

Division 14—Radar 

Division 15—Radio Coordination 

Division 16—Optics and Camouflage 

Division 17—Physics 

Division 18—War Metallurgy 

Division 19—Miscellaneous 

Applied Mathematics Panel 

Applied Psychology Panel 

Committee on Propagation 

Tropical Deterioration Administrative Committee 


Library of Congress 








NDRC FOREWORD 


A s EVENTS of the years preceding 1940 re- 
. vealed more and more clearly the serious¬ 
ness of the world situation, many scientists in 
this country came to realize the need of organ¬ 
izing scientific research for service in a national 
emergency. Recommendations which they made 
to the White House were given careful and sym¬ 
pathetic attention, and as a result the National 
Defense Research Committee [NDRC] was 
formed by Executive Order of the President in 
the summer of 1940. The members of NDRC, 
appointed by the President, were instructed to 
supplement the work of the Army and the Navy 
in the development of the instrumentalities of 
war. A year later, upon the establishment of the 
Office of Scientific Research and Development 
[OSRD], NDRC became one of its units. 

The Summary Technical Report of NDRC is 
a conscientious effort on the part of NDRC to 
summarize and evaluate its work and to present 
it in a useful and permanent form. It comprises 
some seventy volumes broken into groups cor¬ 
responding to the NDRC Divisions, Panels, and 
Committees. 

The Summary Technical Report of each Divi¬ 
sion, Panel, or Committee is an integral survey 
of the work of that group. The first volume of 
each group’s report contains a summary of the 
report, stating the problems presented and the 
philosophy of attacking them, and summarizing 
the results of the research, development, and 
training activities undertaken. Some volumes 
may be “state of the art” treatises covering 
subjects to which various research groups have 
contributed information. Others may contain 
descriptions of devices developed in the labora¬ 
tories. A master index of all these divisional, 
panel, and committee reports which together 
constitute the Summary Technical Report of 
NDRC is contained in a separate volume, which 
also includes the index of a microfilm record of 
pertinent technical laboratory reports and ref¬ 
erence material. 

Some of the NDRC-sponsored researches 
which had been declassified by the end of 1945 
were of sufficient popular interest that it was 
found desirable to report them in the form of 
monographs, such as the series on radar by 
Division 14 and the monograph on sampling 
inspection by the Applied Mathematics Panel. 
Since the material treated in them is not du¬ 
plicated in the Summary Technical Report of 
NDRC, the monographs are an important part 
of the story of these aspects of NDRC research. 


In contrast to the information on radar, 
which is of widespread interest and much of 
which is released to the public, the research on 
subsurface warfare is largely classified and is 
of general interest to a more restricted group. 
As a consequence, the report of Division 6 is 
found almost entirely in its Summary Technical 
Report, which runs to over twenty volumes. 
The extent of the work of a Division cannot 
therefore be judged solely by the number of 
volumes devoted to it in the Summary Technical 
Report of NDRC: account must be taken of 
the monographs and available reports published 
elsewhere. 

One can claim on behalf of Division 11 that 
the results of its work contributed directly and 
dramatically to the successful prosecution and 
triumphant termination of World War II. It 
was Division 11, under the leadership first of 
R. P. Russell, then of E. P. Stevenson, and later 
of H. M. Chadwell, which developed the incendi¬ 
ary bombs with which Japan’s industrial plants 
were reduced to ashes. Filled with jellied gaso¬ 
line, the AN-M69 incendiary was credited with 
the highest efficiency of any bomb against Jap¬ 
anese factories and dwellings. More than 40,000 
tons of AN-M69 bombs were dropped on Jap¬ 
anese cities. 

Division 11 likewise applied the use of thick¬ 
ened fuels to portable and mechanized flame 
throwers, which were employed with great suc¬ 
cess against the enemy in the Pacific. Other 
sections of the Division did important work in 
developing improved techniques for the produc¬ 
tion of oxygen for military uses, and in solving 
numerous other problems in the field of chem¬ 
ical engineering, one of the most valuable con¬ 
tributions being the development of new hy¬ 
draulic fluids. 

This Summary Technical Report of Division 
11, prepared under the direction of the Division 
Chief and authorized by him for publication, 
describes the activities of the Division and its 
contractors. It stands as a testimonial to the 
imagination and resourcefulness of American 
scientists and industrial engineers and as a 
record of wartime accomplishment worthy of 
grateful recognition. 

Vannevar Bush, Director 
Office of Scientific Research and Development 

J. B. CONANT, Chairman 
National Defense Research Committee 


i 


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FOREWORD 


F or administrative purposes and because of 
the diverse nature of the problems studied by 
Division 11 (Chemical Engineering) of NDRC, 
three independent sections were created: Sec¬ 
tion 11.1 (Oxygen Problems), Section 11.2 
(Miscellaneous Chemical Engineering Prob¬ 
lems), and Section 11.3 (Fire Warfare). The 
work of each of the three sections is presented 
in an individual volume of the Summary Tech¬ 
nical Report. 

This volume describes the research and de¬ 
velopment work of Section 11.3 (and its prede¬ 
cessor organizations) in the fields of incendi¬ 
aries, flame throwers, and incendiary fuels. This 
work was carried out under the direction of 
Mr. R. P. Russell (January and February 1943), 
Mr. E. P. Stevenson (March 1943 to February 
1945), and Dr. H. M. Chadwell (March 1945 to 
termination) as Chiefs of Division 11 for the 
periods indicated, and of Mr. N. F. Myers (Jan¬ 
uary 1943 to April 1943) and Dr. H. C. Hottel 
(May 1943 to termination) as Chiefs of Sec¬ 
tion 11.3. Assisting them were Dr. R. H. Ewell, 
Dr. C. S. Keevil, and Dr. C. E. Reed as Section 
Technical Aides, and Mr. S. M. Jones, Dr. E. C. 
Kirkpatrick, Mr. R. E. Loop, and Mr. R. M. 
Newhall as Technical Aides on specific as¬ 
signments. Whereas all the contractors work¬ 
ing under Section 11.3 (listed in an appendix 
to this volume) made valuable contributions, 
particular mention should be made of the con¬ 
tributions of the Standard Oil Development 
Company, Factory Mutual Research Corpora¬ 
tion, Eastman Kodak Company, Massachusetts 
Institute of Technology, Harvard University, 
and Arthur D. Little, Inc., in the fields of in¬ 
cendiaries, flame throwers, and incendiary fuels. 

The editor, and principal contributor, of this 
volume was Dr. Raymond H. Ewell, Technical 
Aide in Section 11.3 (and its predecessor organ¬ 
izations) from December 1941 to January 1946. 
Assistant editor of the volume was Mr. Robert 
M. Newhall, Office of Field Service, OSRD, who 
was later Technical Aide in Section 11.3. Pro¬ 
fessor H. C. Hottel as Chief of Section 11.3 kept 
in close touch with the preparation of the vol¬ 
ume and reviewed all material as prepared by 
the editors. The following authors wrote one or 


more sections under the supervision of the 
editors. 

E. E. Bauer, Eastman Kodak Company 
A. Bogrow, Arthur 1). Little, Inc. 

G. W. Engisch, Standard Oil Development Company 
M. D. Haworth, Standard Oil Development Company 
E. B. Hershberg, Harvard University 
S. M. Hulse, Standard Oil Development Company 
C. S. Keevil, Technical Aide, Section 11.3, and Sec¬ 
tion 11.3 representative at Edgewood Arsenal 

W. T. Knox, Standard Oil Development Company 
E. L. McMillen, Eastman Kodak Company 
R. F. Messing, Office of Field Service, OSRD, and 
Member, Incendiary Evaluation Group, Edgewood 
Arsenal 

K. H. Mysels, Stanford University 
C. E. Reed, Technical Aide, Section 11.3 
G. R. Stanbury, Ministry of Aircraft Production and 
Member, Incendiary Evaluation Group, Edgewood 
Arsenal 

The coordination within the Division was su¬ 
pervised first by R. H. Ewell and later by D. 
Churchill, Jr. To all these men the Division 
Chief wishes to express his sincere thanks. 

The developments described in this volume 
were carried out in close cooperation with the 
Chemical Warfare Service (incendiaries), the 
Army Ground Forces (flame throwers), and 
the Navy Bureau of Ordnance (flame throw¬ 
ers). Besides reporting work done at establish¬ 
ments of Section 11.3 contractors, some work 
on Section 11.3 developments is reported which 
was carried out at Army and Navy establish¬ 
ments, including Edgewood Arsenal, Dugway 
Proving Ground, Huntsville Arsenal, Eglin 
Field, Fort Belvoir, Fort Knox, Fort Benning, 
and others. Particular mention should be made 
of the close liaison and high degree of coopera¬ 
tion with the Chemical Warfare Service, with¬ 
out which the successful completion of many of 
these projects would not have been possible. 

The Division Chief also wishes to acknowl¬ 
edge with thanks the valuable help and guidance 
in broad phases of the program and policy of 
Dr. Roger Adams, member of the NDRC. 

H. M. Chadwell 
Chief, Division 11 
H. C. Hottel 
Chief, Section 11.3 







CONTENTS 


CHAPIKR PAGE 

Summary . 1 

1. Incendiary Bombs and Clusters by R. H. Ewell, 

E. B. Hershberg, and C. S. Keevil .... 7 

2. Miscellaneous Incendiary Items by R. H. Eivell 

and E. B. Hershberg .44 

3. Testing and Evaluation of Incendiaries by 
C. S. Keevil, R. F. Messing, R. H. Ewell, W. 

Knox, and H. C. Hottel .53 

4. Portable Flame Throwers by R. H. Ewell, N. F. 

Myers, A. Bogrow, R. M. Newhall, and G. IF. 
Engisch .95 

5. Mechanized Flame Throtvers by A. Bogrow, 

N. F. Myers, R. M. Newhall, M. D. Haworth, 

and E. E. Bauer .103 

6. Miscellaneous Flame Warfare Items by A. 

Bogroiv, R. M. Newhall, C. E. Reed, N. F. 
Myers, and S. H. Hulse .147 

7. Studies on Flame-Thrower Design by R. M. 

NewhaU and R. H. Ewell .166 

8. Fuels for Incendiaries and Flame Throwers by 
E. K. Carver, E. E. Bauer, R. H. Ewell, A. 
Bogrow, E. L. McMillen, and R. M. Newhall 192 

Glossary.227 

Bibliography.229 

OSRD Appointees.245 

Contract Numbers.247 

Ser\ ice Project Numbers.251 

Index. 253 
















SUMMARY 


T his volume describes the research and de¬ 
velopment work of Section 11.3 (and its 
predecessor organizations) in the fields of in¬ 
cendiaries, flame throwers, and incendiary fuels. 
Chapters 1, 2, and 3 deal with incendiaries. 
Chapters 4, 5, 6, and 7 with flame throwers, and 
Chapter 8 with incendiary fuels. This program 
was carried out under 33 research and develop¬ 
ment contracts with 28 universities and indus¬ 
trial concerns as contractors. The results of this 
work contributed in no small measure to the 
successful prosecution and termination of the 
war, the most spectacular contributions being 
the incendiary bombs with which the Japanese 
cities were bombed and destroyed, and the 
thickened gasoline fuels which were used so 
successfully in incendiaries, flame throwers, 
and “blaze” bombs. 

AN-M69 Incendiary Bomb. The most impor¬ 
tant single development in Section 11.3 was the 
AN-M69 incendiary bomb. This bomb, devel¬ 
oped by the Standard Oil Development Co., was 
a small tail-ejection bomb utilizing jellied gaso¬ 
line as a fuel and deriving much of its elfective- 
ness from the tail-ejection feature. The bomb 
consisted essentially of a hexagonal can of thin 
sheet steel, 2% by 19 1/2 in., weighing 6.2 lb com¬ 
plete, and containing 2.6 lb of jellied gasoline. 
The nose contained an impact fuze with a 3 to 
5 sec delay and a powder charge which ejected 
and ignited the fuel charge. Besides the hori¬ 
zontal tail-ejection principle the bomb em¬ 
bodied two new features in bomb design: (1) a 
horizontally placed impact fuze working by 
means of a hinged striker in lieu of an axial 
firing pin as commonly used in bomb fuzes, and 
(2) cloth tail streamers in lieu of a rigid metal 
tail as commonly used on bombs. Both these 
design features were developed in order to 
economize on the required length of the bomb. 
The bombs were filled with Napalm or polymer- 
type thickened gasoline containing about 90 
per cent gasoline and 10 per cent of thickening 
agent. 

The bombs were assembled in either quick¬ 
opening or aimable clusters of 100- and 500-lb 
sizes. The cluster produced and used in largest 
quantity was the M19 (E46) 500-lb size aimable 


cluster, containing 38 AN-M69 bombs and 
weighing 425 lb complete. Forty of these clus¬ 
ters could be carried on a B-29 bomber. When 
dropped the cluster falls intact in stabilized 
flight until it bursts open at a predetermined 
altitude, usually 5,000 ft. As the individual 
bombs impact on the target they normally come 
to rest in a horizontal position, and after 3 to 
5 sec delay they explode, ejecting the burning 
fuel charge out the tail. If unobstructed, the 
burning fuel charge will travel up to 300 ft 
horizontally, and when it strikes a surface, the 
flaming fuel charge smears out producing a 
mass of flames 6 to 10 ft high. 

In the form of aimable clusters the AN-M69 
bomb had a degree of aimability equal to demo¬ 
lition bombs of the 100-lb class, and hence was 
suited for either area incendiary bombing in 
cities or for precision bombing of specific tar¬ 
gets. The terminal velocity of the individual 
bombs was 220 to 230 ft/sec, practically inde¬ 
pendently of the altitude of release or of open¬ 
ing of the cluster. This velocity was sufficient 
to enable the bomb to penetrate all types of 
domestic roofs and the commoner types of in¬ 
dustrial roofs. 

The fire-starting efficiency of the AN-M69 
bomb was thoroughly tested and found to be 
adequate for starting fires in all types of targets 
for which its use was contemplated. In fact, the 
tests indicated that on factories and on Japa¬ 
nese domestic construction the AN-M69 had 
the highest fire-starting efficiency per cluster, 
or per ton, or per bomber load of any incen¬ 
diary bomb. 

The principal use of AN-M69 bombs in 
World War II was in the bombing and destruc¬ 
tion of the major cities of Japan in the period 
January to August 1945. Over 40,000 tons of 
AN-M69 aimable clusters were dropped on 
Japanese cities with results which are now 
well known in history. Analysis of the results 
indicated that a minimum density of around 
125 tons/sq mile was required to completely 
burn out an area in a Japanese city. 

M69X Incendiary Bomb. This bomb, also de¬ 
veloped by Standard Oil Development Co., was 
an anti-personnel modification of the AN-M69 


1 


2 


SUMMARY 


bomb. The nose contained a time-delay element 
giving time delays up to 6 minutes and a high- 
explosive charge which shattered the nose into 
more than 300 fragments. This weapon was 
highly lethal, particularly at distances up to 
20 ft. The M69X bomb weighed 7.1 lb complete 
and contained 2.0 lb of thickened gasoline fuel. 
Its ballistic properties, penetrating power, and 
fire-starting efficiency did not differ signifi¬ 
cantly from those of the AN-M69 bomb. The 
M69X bomb was placed in production in March 
1945, but none were ever used operationally. 

Aimable Clusters for Incendiary Bombs. 
When the need for aimable clusters became 
apparent, the Chemical Warfare Service de¬ 
signed and produced the E28 (M18) cluster, 
which had certain disadvantages. Then the 
Standard Oil Development Co. developed the 
E18 cluster, which had other disadvantages. 
Finally the Chemical Warfare Service com¬ 
bined the best features of both these clusters 
into the M19 (E46) aimable cluster, which 
proved to be quite satisfactory and was pro¬ 
duced and used extensively in bombing Japan. 

El9 Incendiary Bomb. This bomb, developed 
by Harvard University and Factory Mutual Re¬ 
search Corp., was an 11-lb bomb combining 
magnesium, oil, and thermite as incendiary ma¬ 
terials. It had an extensible metal tail, a steel 
nose piece, and a novel perforated metal sleeve 
to impart strength. The tail cone was hollow 
and contained a charge of white phosphorus 
which gave off a dense white smoke. When the 
tail was in the compressed position, as in a 
cluster, the E19 bomb was identical in size with 
the AN-M69 bomb, and it could be assembled 
in the same clusters. The E19 bomb burned 
with a very hot flame, but its overall fire-start¬ 
ing efficiency was inferior to that of the AN-M69 
bomb. Its only advantage over the AN-M69 
bomb was its greater penetrating power, but 
this factor diminished in importance as the war 
went on, and hence the E19 bomb was never 
seriously considered for production. 

E9 Incendiary Bomb. This bomb developed 
by The Texas Co. was a 40-lb tail-ejection bomb 
with a time-delay, anti-personnel element. This 
bomb was 5 by 29%e> in. in size (with extensible 
tail compressed), and contained 9.5 lb of thick¬ 
ened gasoline fuel and 0.8 lb of white phos¬ 


phorus. It packed 14 bombs in a 500-lb size 
cluster. This bomb was characterized by high 
terminal velocity, great penetrating power, and 
a high degree of aimability. The anti-personnel 
charge contained 0.65 lb of tetrytol, and it was 
an exceedingly lethal weapon. The E9 bomb 
never reached the production stage because 
there was no demand for a very highly pene¬ 
trating bomb in the latter stages of World 
War II, and the size of the bomb gave it a low 
fire-starting efficiency on a cluster basis com¬ 
pared to any of the small bombs. However, the 
bomb incorporated a number of novel features 
of design which should be of interest to future 
bomb designers. 

One novel feature of the E9 bomb was the 
cluster designed for its use. Because of the 
intrinsic aimability of the bomb it was not nec¬ 
essary to assemble it in aimable clusters, and 
yet it was necessary to provide a cluster mech¬ 
anism which would not give rise to dangerous, 
slowly falling metal parts. This was accom¬ 
plished by making a cluster mechanism consist¬ 
ing of pipes of spear-like members bound 
together with strong metal cables. These cluster 
parts fell sufficiently fast that they constituted 
no hazard for aircraft flying below the drop¬ 
ping airplane. Yet the cluster was the strongest 
ever produced, sustaining 18 G downward 
stress. 

Miscellaneous Incendiary Items. Besides the 
major incendiary bombs, a number of minor 
incendiary items were developed, of which 
three were used in World War II. A new type 
of burster was developed by Harvard Univer¬ 
sity for the AN-M47 type of bombs embodying 
a tube of white phosphorus with a core of TNT 
or other high explosive. This burster was a 
replacement for the older black powder type of 
burster. Harvard University developed two 
small hand incendiaries, one a fire starter for 
emergency use and the other a sabotage incen¬ 
diary, both of which were produced and used in 
the war. Both were eventually of thickened 
gasoline contained in a celluloid case. The Ml 
fire starter was a small cylinder with a match 
striker ignition mechanism. The H2 vest-pocket 
sabotage incendiary resembled a cigarette case, 
and was equipped with a delay incendiary pen¬ 
cil ignition mechanism. 



SUMMARY 


3 


Testing and Evaluation of Incendiaries. 
Many methods for testing incendiaries were 
devised and used by Section 11.3 and its con¬ 
tractors, ranging from small laboratory tests to 
large-scale tests involving model villages and 
factories. The most significant were the full- 
scale tests on the German Japanese village at 
Dugway Proving Ground, which was designed 
and supervised in construction by the NDRC 
Standard Oil Development Co. groups, and the 
model factory tests carried out by the Incen¬ 
diary Evaluation Project at Edgewood Arsenal. 

The full-scale tests at Dugway Proving 
Ground gave the first reliable indication of the 
effectiveness of the AN-M69 bomb on Japanese 
domestic structures, and the results of the tests 
were used by the Army Air Forces in the fall of 
1943 for drawing up preliminary plans for 
bombing Japanese cities. The Dugway results 
were later checked by tests on a standardized 
model Japanese room by the Incendiary Evalu¬ 
ation Project at Edgewood Arsenal. 

In the factory tests of the Incendiary Evalu¬ 
ation Project typical combustible objects pres¬ 
ent in factories, such as workbenches, storage 
bins, packing cases, cardboard cartons, and 
wooden partitions were tested with various 
bombs under realistic conditions such that a 
mathematical extension of the data to an actual 
factory layout gave absolute fire-starting prob¬ 
abilities, which it would require long and costly 
airborne tests to duplicate. These tests indi¬ 
cated the AN-M69 and AN-M50 bombs to be 
about equal, and the M74 somewhat inferior, 
for use in factories. 

Portable Flame Throivers. In the summer of 
1942 the Armv Ml portable flame thrower was 
modified by the Standard Oil Development Co. 
to allow the use of the newly developed thick¬ 
ened fuels. The resulting MlAl Model was used 
extensively during 1942 and 1943 in the Pacific 
War. The changes consisted of a more efficient 
type of fuel control valve and an increased 
opening and other adjustments in the pressure 
regulator. These changes increased the range 
from 20 to 25 yd for the Ml Model to 45 to 50 yd 
for the MlAl, and demonstrated the practica¬ 
bility of using thickened fuel. 

The MlAl Model left much to be desired in 
flame-thrower performance so that an im¬ 


proved portable flame throw'er, the E2 Model, 
was developed by Standard Oil Development 
Co. in the winter of 1942-1943. This model em¬ 
bodied a cylindrical roundheaded fuel tank en¬ 
circled by an oval “doughnut”-type compressed 
air tank. Maximum use was made of aluminum 
as a structural metal resulting in a large fuel 
capacity in relation to the gross weight. Other 
improvements included an improved ignition 
system using gasoline instead of hydrogen, 
diminished pressure loss in the fuel system, im¬ 
proved accessibility of controls and a scientifi¬ 
cally designed carrying frame. The E2 Model 
had only a small superiority in range over the 
MlAl Model, but it was vastly superior in full 
capacity, reliability, and ease of operation. The 
E2 Model was never put into production be¬ 
cause of the simultaneous development of a 
competitive model, M2-2, by the Chemical War¬ 
fare Service. 

Some work was carried out on one-shot ex¬ 
pendable flame throwers utilizing both pistons 
and collapsible tubes as media for transmitting 
pressure to the fuel, but none were brought to 
the production stage. 

Mechanized Flame Throivers. NDRC com¬ 
menced development work on mechanized flame 
throwers in March 1942. During the course of 
this program, 11 different mechanized flame 
throwers, consisting of a flame gun, fuel tanks, 
compressed air tanks, and controls, mounted 
on a tank or other fighting vehicle, were de¬ 
veloped. In addition, several experimental, 
long-range flame guns were developed which 
were not mounted on vehicles. All the flame 
guns, except two, used compressed air as the 
source of pressure. The other two, still in de¬ 
velopment at the close of World War II, used a 
pneumatic ram and a pump, respectively, as 
sources of pressure. None were developed using 
propellant powder as a source of pressure. Two 
of the complete mechanized flame throwers, 
E7-7 and Navy Mark I, saw combat service in 
the Pacific war, and another, M5-4, was in 
large-scale production at the end of the war. 
One flame gun and four of the complete mech¬ 
anized units, all developed by Standard Oil 
Development Co., will be described separately 
and the other models will be mentioned only 
briefly. 



4 


SUMMARY 


E7 Flame Gim. This flame gun, developed by 
Standard Oil Development Co. in the winter of 
1942-1943, was the culmination of earlier mod¬ 
els A, B, C, and D. It was immediately success¬ 
ful, and it became the standard United States 
flame gun. It had a maximum range of over 
125 yd for covering operations when applied to 
open trenches or fox holes, and an effective 
range of at least 50 yd when penetrating small 
enclosures such as pill box embrasures. In gen¬ 
eral principles it resembled standard portable 
flame throwers, but constructed much heavier 
and on a larger scale. A i/o-in. nozzle was used 
on the early models and interchangeable V^-in. 
and %-in. nozzles on later models (E7R1 and 
E7R2). The fuel control valve was located far 
back of the nozzle in contrast to the pintle 
valve in the nozzle itself as was standard 
British practice. An important new feature was 
the use of a secondary fuel of liquid gasoline 
which was applied in small quantity to the main 
stream of thickened gasoline fuel through a 
porous iron annulus at the nozzle. This feature 
improved both range and ignition. The ignition 
system used atomized gasoline and a rugged 
high-tension spark plug. Models E7R1 and 
E7R2 were improved models differing only in 
detail from E7. This flame gun was produced 
by Lecourtenay Co., and used on all four of the 
mechanized flame throwers described below. 

E7-7 Mechanized Flame Thrower. This was 
the first complete mechanized flame thrower de¬ 
veloped by NDRC. It consisted of an E7 flame 
gun and an E7 fuel system mounted in an 
M5A1 light tank. The gun, fuel tanks, com¬ 
pressed air tanks, and controls were all con¬ 
tained in a self-contained, turret-basket assem¬ 
bly which could be placed in any M5A1 tank 
hull. The complete system, filled with fuel (125 
gal), added 2,650 lb to the weight of the tank. 
This arrangement eliminated the 37-mm gun 
main armament of the M5A1 Tank. This unit 
was developed by Standard Oil Development 
Co., and four complete units were fabricated by 
Cadillac Motor Car Co. These units saw service 
in the Philippine Islands in June 1945, but the 
few results only indicated the potentialities of 
this type of weapon. 

Navy Mark I Flame Throtver. This model is 
of interest as the first long-range, large-capacity 


mechanized flame thrower ever used in combat 
by U. S. Forces. The Navy Mark I Model con¬ 
sisted of an E7 flame gun mounted with fuel 
tanks, air tanks, and controls in an armored, 
self-contained box-like unit, weighing about 
6,000 lb when filled with fuel (200 gal). The 
range and other operating characteristics were 
the same on the E7-7 Model since the E7 flame 
gun was used in both. This model was originally 
introduced for use in the cockpits of landing 
craft for attack of beach fortifications, but they 
actually were used in LVT-4 amphibious trac¬ 
tors. The Navy Mark I Model was developed 
by Standard Oil Development Co. Twenty-one 
units were manufactured by M. W. Kellogg Co. 
Six units saw service on Pelelieu Island in Sep- 
tember-November 1944, where they were highly 
effective. 

EH-7R2 Mechayiized Flame Throiuer. This 
model consisted of an E7R2 flame gun mounted 
with an E14 fuel system in an LVT-Al am¬ 
phibious tank. This unit was developed by 
Standard Oil Development Co., and the first 
unit was fabricated by Lima Locomotive Works 
and later units by M. W. Kellogg Co. None were 
ever used in combat. 

M5-Jf. (E12-7R1) Mechanized Flame Thrower. 
This model, designed by Standard Oil Develop¬ 
ment Co. and manufactured by M. W. Kellogg 
Co., consisted of an E7R1 flame gun and an 
E12 fuel system in an M4A1 or M4A3 medium 
tank. The fuel and air tanks were housed in 
both the hull and turret basket so that it was 
not a self-contained, turret-basket assembly as 
the E7-7. The fuel capacity was 315 gal com¬ 
pared to 125 gal for the E7-7. As in the E7-7, 
the flame thrower displaced the normal main 
armament of the tank. The performance of this 
model was essentially the same as the E7-7 
Model. The MS-4 was standardized by the Army 
for large-scale production, and about 75 units 
had been completed and about 600 were on 
order at the close of World War 11. None were 
ever used in combat. 

Other Mechanized Flame-Throiver Models. 
Model E8, developed by C. F. Braun and Co., 
was mounted in an M5A1 light tank with sta¬ 
tionary turret body. Model 1-3, developed by 
Shell Development Co., was a simplified flame 
gun which was never mounted on a vehicle. 



SUMMARY 


5 


Model E9, developed by Standard Oil Co, (In¬ 
diana), had an original design flame gun with 
i/4-in. and %-in. interchangeable nozzles 
mounted in an M5A1 light tank and equipped 
with a 1,200-gal armored fuel trailer. Model 
E13-13, developed by Morgan Construction Co., 
used a pneumatic ram as the source of pressure 
with an E13 flame gun of the pintle valve type 
and an E13 fuel system mounted in an M4A1 
medium tank. Model E13R1-13R2, developed by 
Massachusetts Institute of Technology, was a 
modified form of the E13-13 Model, only using 
compressed air instead of a pneumatic ram as 
the source of pressure. Model 19-19, which was 
being developed by the State University of 
Iowa when World War II ended, was the first 
United States design to retain the normal main 
armament of the tank and still provide a long- 
range effective flame thrower as an auxiliary. 
After studying several possible locations for in¬ 
stallation of such a flame thrower in the M4A3 
medium tank, a location on the port side of the 
turret was selected for further development. 
Model E20-20 (Ordnance designation T33), 
which was in development jointly by Standard 
Oil Development Co., Chemical Warfare Serv¬ 
ice, and Ordnance Department at the close of 
the war, was similar to the M5-4 Model, except 
that the main tank armament was retained and 
the flame gun was mounted coaxially with the 
tank’s 76-mm gun. If the war had continued, 
the E20-20 Model would probably have re¬ 
placed the then standard M5-4 Model. A pump- 
operated flame thrower was in development by 
Eastman Kodak Co. at the close of World 
War II. 

Flame Throiver Servicing Units. Model E8 
flame-thrower servicing unit, developed by 
Standard Oil Development Co. and Davey Com¬ 
pressor Co., comprised a thickened fuel mixing 
tank, fuel storage tanks, an air compressor, 
and air storage tanks mounted on an Army 
truck. A power take-off from the truck engine 
provided power. This unit provided complete 
field servicing facilities for flame throwers. 
Sixty-five units were made, of which some were 
sent to the field. The mixer and compressor 
were also mounted separately as palletized units 
for carrying in small landing craft. Other fuel 
mixing units were developed by other contrac¬ 


tors for use with portable flame throwers and 
for shipboard use for filling “blaze” bombs. 

El Anti-Personnel Taiik Projector. This unit, 
the purpose of which was to harass infantry 
attacking tanks at close range, consisted of a 
small tank filled with a spontaneously inflam¬ 
mable liquid mixture of phosphorus and sulfur, 
and fitted with a nozzle controlled from inside 
the tank. The phosphorus fuel had a strong 
anti-personnel effect, and also produced a thick 
white smoke. 

Studies on Flame-Throiver Design. Extensive 
studies were made by Massachusetts Institute 
of Technology, Factory Mutual Research Corp., 
Standard Oil Development Co., Eastman Kodak 
Co., and other contractors on the fundamentals 
of design and fuel properties which determine 
flame-thrower performance. These studies con¬ 
tributed materially to the efficient design of 
many of the flame throwers described herein. 

Fuels for Incendiaries and Flame Throivers. 
The type of fuel used most widely in the above 
weapons was jellied or thickened gasoline. The 
value of thickened fuel in incendiaries and 
flame throwers was demonstrated by the early 
fundamental work at MIT and Standard Oil 
Development Co. The most important agent for 
thickening gasoline developed in World War II 
was “Napalm,” an aluminum soap of naph¬ 
thenic, oleic and coconut oil acids. Napalm was 
a cooperative development resulting from the 
coordinated efforts of Harvard University, Nu- 
odex Products Co., Eastman Kodak Co., and the 
Standard Oil Development Co. About 80,000,000 
lb of Napalm were produced and used in many 
applications. Napalm is a generic term, and the 
composition can vary widely, although the most 
commonly used acid composition contained 25 
per cent naphthenic acid, 25 per cent oleic acid, 
50 per cent coconut oil acids. The successful 
commercial production of this material in¬ 
volved coprecipitation and drying to form a dry 
granular powder resembling some commercial 
soap powders. The variables in the production 
of Napalm were thoroughly studied, and this 
resulted in the production of a reliable, uniform 
product. 

The use of Napalm on shipboard for filling 
“blaze” bombs led to the desirability of having 
a liquid thickening agent which could be mixed 




6 


SUMMARY 


with gasoline in a continuous two-stream opera¬ 
tion. Several liquid thickening agents were 
studied, of which aluminum cresylate (plus 
stearic acid dissolved in gasoline) was the most 
promising. 

Early in World War II thickening agents 
which were based on isobutyl methacrylate 
polymers fortified with sodium soaps were de¬ 
veloped by E. I. du Pont de Nemours and Co., 
Ammonia Department, for filling incendiary 
bombs. 

Fortified fuels for use in both incendiary 
bombs and flame throwers were studied by sev¬ 
eral contractors. The principal advantages 
sought were greater fierceness of burning and 
more difficult extinguishment by water com¬ 
pared to thickened gasoline. Most of these con¬ 
sisted of hydrocarbon base fuels with added 


finely divided metals, such as magnesium, 
and/or oxidizing agents, such as nitrates. 

Self-igniting fuels were the subject of study 
by Arthur D. Little, Inc., and other contractors. 
The most useful one discovered was a liquid 
eutectic mixture of phosphorus and sulfur men¬ 
tioned in connection with the El Anti-Person¬ 
nel Tank projector. 

An extensive program of fundamental studies 
on the rheological properties of thickened gaso¬ 
line was carried out by Eastman Kodak Co., 
which permitted a sound, scientific approach to 
many of the problems involved in the manu¬ 
facture and use of Napalm. While many inter¬ 
esting and scientifically valuable results were 
obtained, little correlation with the perfor¬ 
mance of incendiary bombs and flame throwers 
was discovered. 



Chapter 1 

INCENDIARY BOMBS AND CLUSTERS 


INTRODUCTION 

I NCENDIARY BOMBS WERE Used ill World War 
II by all belligerents, but most effectively by 
the British, United States and German air 
forces. Incendiary bombs were used against 
three principal types of targets: 

1. Heavy domestic construction as in Ger¬ 
many or Great Britain. 

2. Light domestic construction as in Japan 
and other parts of the Orient. 

3. Factories, warehouses and other precision 
bombing targets. In the attack of British cities, 
the German air force used 10 to 30 per cent 
incendiary bombs. Profiting by this example, 
the British air force used 30 to 70 per cent in¬ 
cendiaries in their attack of German cities. In 
the attack of Japanese cities, the United States 
air force used essentially 100 per cent in¬ 
cendiary bombs. In the attack of factory targets 
by precision bombing, the U.S. air force used 
incendiary bombs in variable amounts, ranging 
all the way from 0 to 100 per cent, but usually 
around 20 to 50 per cent. 

For the purpose of orientation the principal 
incendiaries used or developed to an advanced 
stage in World War II may be classified as 
follows. 

1. Small incendiary bombs, 2 to 11 lb. 

2-lb United States magnesium bomb, 
AN-M52. 

2.2-lb German magnesium bomb, Bl. 

4-lb British magnesium bomb, Mark IV. 
4-lb United States magnesium bomb, AN- 
M50. 

4-lb United States therm-8 bomb, AN- 
M54. 

5-lb German magnesium bomb, B2.2. 

6-lb United States gasoline gel bomb, AN- 
M69. 

6-lb United States gasoline gel bomb, 
M69X. 

8-lb United States pyrotechnic gel bomb, 
M74. 

11-lb United States magnesium bomb, 
E19. 


2. Medium-sized incendiary bombs, 18 to 

40 lb. 

18-lb British magnesium dust bomb, 
Mark I. 

20-lb British naphthalene jet bomb, J20. 

30-lb British gasoline gel bomb, Mark IV. 

30-lb British liquid gasoline jet bomb, J30. 

40-lb United States gasoline gel bomb, E9. 

3. Large incendiary bombs, 70 to 550 lb. 

70-lb U.S. gasoline gel bomb, AN-M47. 

75-lb German fire-pot bomb, Sprengbrand 

C.50. 

90-lb German benzene-phosphorus bomb. 
Brand C.50. 

240-lb German benzene-phosphorus bomb, 
Brand C.250. 

240-lb German gasoline gel bomb. Flam 
C.250. 

250-lb British gasoline gel bomb, Mark II. 

400-lb British gasoline gel bomb, Mark 1. 

500-lb U.S. pyrotechnic gel bomb, AN-M76. 

550-lb German gasoline gel bomb, Flam 
C.500. 

4. Super incendiaries, over 550 lb. 

1,000-lb British gasoline gel bomb, Mark I. 

4,000-lb British gasoline gel bomb. 

United States jettisonable gasoline tanks 

(fire bombs), 75- to 300-gal capacity. 

5. Miscellaneous small incendiaries. 

Incendiary leaves. United States and 

British. 

Sabotage incendiaries (for hand place¬ 
ment) . 

This list includes both service types and the 
principal bombs in development at the close of 
the World War 11. Not included in the list are 
(1) numerous abortive experimental incendiary 
bombs, (2) numerous minor variants of the 
above bombs, (3) Japanese, Italian, French, and 
Russian incendiary bombs, none of which were 
significant in World War 11. 

The first two categories of incendiary bombs, 
namely small and medium-sized bombs, are or¬ 
dinarily provided and used in containers or 
clusters of some description. Such clusters may 
be either the quick-opening or short-delay type 


7 


8 


INCENDIARY BOMBS AND CLUSTERS 


which open almost immediately below the air¬ 
plane, or the aimable or projectile type, which 
are stabilized and provided with a time or 
barometric fuze allowing them to be dropped 
intact for thousands of feet before opening. 
The third and fourth categories, namely large 
incendiary bombs and super incendiaries, are 
ordinarily hung individually on either internal 
or external bomb racks. However, the AN-M47 
bomb is usually loaded in multiple suspension 
with two to six bombs hung on a single bomb 
station. 

Incendiary bombs may also be classified ac¬ 
cording to the mode of functioning as follows. 

1. Static functioning type, which burns 
where it comes to rest. 

a. With undirected combustion, e.g., mag¬ 
nesium bombs. 

b. With directed combustion, e.g., jet 
bombs. 

2. Distributive type, which throws incendi¬ 
ary material some distance from the point 
of initial impact or the point of rest. 

a. Instantaneous firing type. (1) Bursting 
type, which bursts the incendiary 
bomb, dispersing chunks of the in¬ 
cendiary charge outwards and down¬ 
wards in a conical pattern due to the 
downward inertia, e.g., AN-M47 bomb. 
(2) Tail-ejection type, which ejects the 
incendiary charge out the tail some¬ 
where between the roof and floor of 
the target, e.g., M74. 

b. Delayed firing type. Tail-ejection type, 
which ejects the incendiary charge out 
the tail laterally after a time delay 
sufficient to allow the bomb to come to 
rest, e.g., AN-M69 bomb. 

An incendiary bomb consists essentially of 
some sort of casing filled with an incendiary 
material. Materials which have been most prom¬ 
inent in the development of incendiary bombs 
in World War II are the following: 

Btu per lb 


Magnesium 

Gasoline gel. United States 
motor gasoline 
Gasoline gel, British high 
benzol 

Pyrotechnic gel, several types 


10,800 

16,000 to 17,000 

17,000 to 18,500 

12,000 


Incendiary bombs containing gasoline gel are 
frequently referred to as oil incendiary bombs. 
This is really a misnomer, but the term has be¬ 
come established through usage. A number of 
other incendiary materials were investigated 
which proved to be of little or no value as 
primary incendiary materials, of which the fol¬ 
lowing might be mentioned: 

Btu per lb 

Thermite, including many variants 1,400 
White phosphorus 10,500 

Celluloid 7,200 


12 AN-M69, 6-LB OIL INCENDIARY BOMB 
Introduction 

Development of this bomb was initiated in 
October 1941 by the Standard Oil Development 
Co. under Contract OEMsr-183 (later super¬ 
seded by Contract OEMsr-354). This develop¬ 
ment was started as a consequence of a letter 
from General H. H. Arnold to Vannevar Bush 
on September 24, 1941, emphasizing the serious 
shortage of magnesium and requesting the de¬ 
velopment of a substitute for magnesium as an 
incendiary material. This project was later 
formalized as Service Project CWS-21 from the 
Chemical Warfare Service on October 7, and 
the work was carried out in direct collaboration 
with the Chemical Warfare Service. 

Following a review of the various incendiary 
bomb designs in use or in development in the 
fall of 1941, exploratory work on the new bomb 
developed the following basic conceptions. 

1. Use of some petroleum product as the in¬ 
cendiary material because of the high heat of 
combustion, 17,500 to 19,500 Btu per lb. 

2. Use of fuel in the form of a gel or other 
semi-solid, in order to control the rate of burn¬ 
ing. 

3. Tail ejection of fuel charge, in order to 
project the fuel charge into a favorable location 
for starting a fire. 

4. Delay fuze, in order to allow the bomb to 
come to rest on its side and eject the fuel charge 
horizontally. 

5. Horizontally placed fuze, in order to econ¬ 
omize on the available length of the bomb. 



AN-M69, 6-LB OIL INCENDIARY BOMB 


9 


6. Use of a comparatively thin metal case, in 
order to yield as high a charge/weight ratio as 
possible. 

7. Cloth streamer tails, in order to stabilize 
the bomb and slow it down to a striking velocity 


bomb consists of a hexagonal thin steel case, 
191/2 in. in length, before release of tail stream¬ 
ers, and 2% in. across the flats, weighing 6.2 lb 
complete and containing about 2.6 lb of gasoline 
gel (Figure 1). The principal components are 





M 69 


- TAIL STREAMERS-► 

(FOLDED IN POSITION) 

- CHEESECLOTH SOCK - 

(ENCLOSING INCENDIARY GEL) 


INCENDIARY GEL FUEL CHARGE 
2.2 LB. 2.6 LB. 


0.4LB WHITE PHOSPHORUS CHARGE 
(ENCLOSED IN PLASTIC CUP) 


- Ml FUZE 


Figure 1. AN-M69 incendiary bomb, external and cross-section views. Model M69-WF (center view) was 
in production at end of World War II but was never used. 


appropriate for the thin case, and to accomplish 
this as economically as possible with respect to 
length of the bomb. 

Description 

Brief Description .^’As finally devel¬ 
oped and produced, the AN-M69 incendiary 


briefly described below. 

1. Casing, hexagonal in shape, made of 19- 
gauge steel, butt-welded, extending the entire 
length of the bomb. In later production begin¬ 
ning May 1945, the tail end of the casing was 
rounded.®’ ” 

2. Nose cup, made of 13-gauge steel, brazed 
into the nose end of the casing. It forms a flat 























10 


INCENDIARY BOMBS AND CLUSTERS 


nose and serves to house the fuze and two con¬ 
tainers of powder. 

3. Fuze, bomb, Ml, of the inertia type, em¬ 
bodying a 3- to 5-second delay train (Figure 
2).®’^ The components of the fuze include a 
base and a hinged striker made of aluminum, 
a hinge pin, a spring, a firing pin, a primer cap, 
a delay spitter fuze, a black powder-magnesium 
powder booster charge in a celluloid cup, a 
safety plunger unit, and a cylindrical fuze case. 



Figure 2. Detail of nose end of AN-M69 incendi¬ 
ary bomb. (Model with WP cup illustrated.) 


The fuze is screwed into a threaded hole in the 
side of the casing and nose cup, and it rests 
directly on the indented bottom of the nose cup. 
The outside face of the fuze bears an arrow 
which should point towards the tail of the bomb. 
In late 1944 an all-ways fuze was developed for 
the M69 bomb, but the stability of the bomb was 
such that it was not needed and it never went 
into production (see Section 2.7). 


4. Powder containers, two in number, made 
of celluloid and filled with an ejection-ignition 
charge consisting of a mixture of black powder 
and magnesium powder. The two powder con¬ 
tainers fit into the nose cup on either side of the 
fuze. 

5. Impact diaphragm assembly, made of 
3/16-in. steel, consisting of a hexagonal mem¬ 
ber resting on the nose cup, and an impact plug 
resting loosely in a hole in the hexagonal mem¬ 
ber. The impact diaphragm assembly takes the 
impact force of the fuel charge when the bomb 
strikes and yet allows ready venting of the 
ejection-ignition charge when the bomb fires. 

6 . Sealing diaphragm, made of 34-gauge 
sheet steel, which covers the impact diaphragm 
assembly and nose cups, and is brazed into the 
bomb assembly between the casing and the nose 
cup. The sealing diaphragm forms a hermetical 
seal for the nose end of the casing, and is sup¬ 
ported by the impact diaphragm for strength. 

7. Tail cup, made of 26-gauge sheet steel, 
crimped into the tail end of the casing similar 
to a tin-can seal, providing a hermetical seal 
for the tail end of the casing. 

8 . Tail retainer assembly, made of sheet steel, 
consisting of a tail retainer cup welded to the 
bottom of the tail cup, a tail retainer disk 
which snaps over the tail retainer cup and holds 
the tail streamer in place, and a tail retainer 
clip which is wedged across the tail cup in a 
way so that the tail retainer assembly cannot 
come out in case the weld between the tail re¬ 
tainer cup and the tail cup should fail. 

9. Tail streamers, four in number, each 3x40 
in. long, made of mildew-proofed sheeting. The 
streamers are held in the tail cup by the tail 
retainer disk, and are folded loosely in the cup. 

10. Gasoline gel filling, 2.6 lb in weight, con¬ 
tained in a cheesecloth sack. The gasoline gel 
may be either of the Napalm type (NP) or the 
isobutyl methacrylate type (IM). 

11 . WP cup, screwed-top plastic cup contain¬ 
ing 6 oz of cast white phosphorus, which is 
located between the sealing diaphragm and the 
gasoline gel fuel charge.^"- This component 
was introduced in the spring of 1945 after ap¬ 
proximately 20,000,000 AN-M69 bombs of the 
above description had already been made with¬ 
out it. This model of the AN-M69 weighed 6.4 










AN-M69, 6-LB OIL INCENDIARY BOMB 


11 


Ib complete and contained 2.2 lb of gasoline gel. 
None was ever used operationally. 

Details of Design.^' - The following presents 
further details regarding each of the com¬ 
ponents of the bomb outlined above, including 
the factors which led to the final selection of 
characteristics and, wherever pertinent, various 
alternatives which were tried and discarded: 

1. Casing. The casing was made hexagonal in 
shape for efficient clustering and to provide a 
firm abutment between adjacent bombs in order 
to keep the safety plungers of all bombs de¬ 
pressed while in clusters. A later model pro¬ 
duced in 1945 was made round at the tail 
end to facilitate seaming.^’’ ‘ Electrically butt- 
welded tubing was selected instead of seamless 
tubing, since the former was equivalent in 
strength for this particular bomb and could be 
butt-welded directly in the hexagonal form, 
whereas seamless tubing was more limited in 
supply and also had to be especially formed to 
the hexagonal shape over a mandrel. Lap weld¬ 
ing was not suitable because it gave an un- 
symmetrical distribution of stresses which re¬ 
sulted in splitting on impact. The thickness of 
sheet steel was selected as 19 gauge, since 20 
gauge proved to be not quite strong enough for 
impact on concrete at terminal velocity, and 
18 gauge was considered heavier than necessary. 
The corners of the hexagonal case were rounded 
in order to eliminate thinning and consequent 
splitting at the corners of the case on impact. 
Low carbon steel, SAE 1010 or its equivalent, 
was used since this was the most available grade 
of steel and was adequate for the purpose. 
Obviously, the grade of steel, the thickness used, 
and the striking velocity of the bomb are inter¬ 
dependent factors, but this particular combina¬ 
tion proved to be satisfactory. 

2. Nose cup. For this component 13-gauge 
steel, SAE 1010 or its equivalent, was selected 
on the same general basis as the casing. The 
nose cup was brazed into the nose end of the 
casing by a continuous copper brazing method 
in a hydrogen atmosphere, with the thin sealing 
diaphragm placed between the nose cup and the 
casing before brazing so that all three com¬ 
ponents were brazed together. This process de¬ 
pends on the surface tension of the molten cop¬ 
per to make a perfect hermetical seal, and it 


was found superior to silver soldering and other 
competitive processes. The brazing process also 
annealed the casing, relieving stresses by the 
butt-welding process. The bottom of the nose 
cup was indented for the purpose of supporting 
the fuze. 

3. Fuze, bomb, Ml.^’** The principal com¬ 
ponents of the fuze, namely, the base and the 
hinged striker, were made of aluminum alloy 
by die casting because this was the simplest 
method of making them. Alternative models 
made of brass or pressed steel were discarded. 
The base contained recesses for the primer cap, 
the delay spitter fuze, and the safety plunger 
unit, and the hinged striker accommodated the 
firing pin. These two principal components were 
assembled by means of the hinge pin and the 
spring, and the whole assembly inserted into 
the cylindrical fuze case. Four different primer 
caps were tried: New No. 4, Mark V, M26, and 
No. 209B. The last was found to be the best. 
The New No. 4 primer was rejected because of 
a high rate of deterioration at high tempera¬ 
tures; the Mark V primer was also subject to 
deterioration but was fairly satisfactory; the 
M26 primer required a stabbing type firing pin 
and was too sensitive. A delay fuze was desired 
in order to allow the bomb to come to rest on 
its side before firing, and for this purpose 
Ensign-Bickford lead-coated spitter fuze, pro¬ 
viding a 3- to 5-sec delay, was selected. In order 
to insure transmission of ignition from the 
primer to the spitter fuze it was found neces¬ 
sary to place a small dab of match composition 
on the receiving end of the spitter fuze. In order 
to insure transmission of ignition from the 
spitter fuze to the booster charge on the back 
of the fuze it was necessary to extend the spitter 
fuze beyond the end of its channel in the fuze 
base and bend it upwards 1/2 in. into the middle 
of the booster charge. The safety plunger unit 
was the standard British-United States design 
used in the 4-lb magnesium and other incendiary 
bombs. The firing pin was of the round-headed 
type, 0.040-in. radius, made of SAE 1112 steel. 
Numerous tests showed that this type of firing 
pin was more reliable than the sharp-pointed 
stabbing type. The sensitivity of the fuze de¬ 
pends on the weight of the hinged striker and 
the strength of the spring. The spring selected 



12 


INCENDIARY BOMBS AND CLUSTERS 


was a 3-turn spring made of 0.055-in. spring 
steel wire. This combination gave zero proba¬ 
bility of firing when dropped two feet onto con¬ 
crete and 100 per cent probability at six feet. 
The booster charge located at the back of the 
fuze consisted of one gram of a mixture of 50 
per cent A-4 black powder and 50 per cent 
Grade B magnesium powder in a flat celluloid 
cup. 

4. Ejection-ignition charge consisted of 0.27 
oz A-4 black powder and 0.23 oz Grade B mag¬ 
nesium powder. Black powder alone did not give 
reliable ignition of the fuel charge at low tem¬ 
peratures. Various grades of aluminum and 
magnesium powder were tried to overcome this, 
and Grade B linseed oil-coated magnesium 
powder was found to be the best. 

5. Impact diaphragm was made in a two- 
piece assembly embodying a loose center plug 
after tests showed that a solid impact dia¬ 
phragm was frequently held by a collapsed or 
distorted casing and interfered with ignition 
of the fuel charge. 

6. Sealing diaphragm was selected of a thick¬ 
ness (34 gauge) which would stand rough treat¬ 
ment during assembly and still be thin enough 
to rupture reliably with the ejection-ignition 
charge selected. Bursting pressure was 450-550 
lb per sq in. 

7. Tail cup was crimped into the casing in 
standard seaming machinery used in the can¬ 
ning industry. Although the hexagonal closure 
gave some difficulties, it was used during 1943 
and 1944, but in 1945 a round closure was 
adopted for easier seaming. It was necessary to 
control hardness of the tail cup from 55 to 70 
on Rockwell B scale in order to get proper 
seaming. A vinylite seaming compound was 
used in the seam to insure gas-tightness. 

8. Tail-retainer assembly was adopted which 
spread the tail streamers to the periphery of 
the tail cup, after early models with a central 
tail suspension gave a large percentage of un¬ 
stable bombs. The tail retainer clip was devised 
as an added precaution after it was found that 
the weld between the tail retainer cup and the 
tail cup sometimes failed. 

9. Tail streamers of bombs in quick-opening 
clusters were made of surgical gauze in early 
models, but the switch to aimable clusters in 


1943 necessitated changing the tails to cotton 
sheeting.^-^ When the bombs are clustered, the 
last 3 in. of the tail streamers are turned back 
outside the bomb to enable the wind to whip 
the tails out reliably and rapidly when released 
from the cluster. The tails were mildew-proofed 
by dipping in a naphtha solution of copper 
naphthenate containing one per cent by weight 
of copper. 

10. Gasoline gel fillings will be described in 
the next section. 

11. WP cup was made of either Bakelite or 
Catalin plastic. The thickness and quality of the 
plastic were selected in order not to break with 
ordinary handling of the bombs and clusters, 
yet break reliably on impact at terminal ve¬ 
locity. The white phosphorus is not intended 
to aid in ignition of the fuel charge, but only 
to provide smoke for the purpose of interfering 
with fire-fighting. The wet phosphorus tended to 
develop cracks in the plastic by action of phos¬ 
phorus acids; therefore sodium acetate was 
added as a buffer. 

Fillings for Bomb. Many types of thickened 
or bodied gasoline fuels were studied as filling 
for the AN-M69 bomb. The heat contents (Btu) 
of all these fuels were essentially the same and 
all fuels showed some degree of effectiveness in 
starting fires, but comparative burning tests 
showed certain fuels to be significantly superior 
to others. The principal requirements, in addi¬ 
tion to fire-starting effectiveness, were (1) suf¬ 
ficient strength to withstand ejection without 
excessive shattering, (2) consistency which 
would give a burning time of 5 to 10 min when 
spread in a (4 in. thick pad, (3) ease of ignition 
by the M69 ejection-ignition charge at tem¬ 
peratures down to 40 degrees below zero, (4) 
availability of required raw materials, and (5) 
ease of manufacture. 

The three principal fuels which were used for 
filling AN-M69 bombs were the following. 

Napalm Filling (NP Type II) 


Napalm thickener 9.0% 

Gasoline 91.0% 

IM Filling 

Isobutyl methacrylate polymer NR 5.0% 

Fatty acids (stearic acid) 2.5% 

Naphthenic acid 2.5% 

Aqueous solution of caustic soda (40%) 3.0% 

Gasoline 87.0% 


C' 



AN-M69, 6-LB OIL INCENDIARY BOMB 


13 


IM Filling (IM Type III) 

Isobutyl methacrylate polymer AE 2.0% 

Fatty acids (stearic acid) .3.0% 

Naphthenic acid 3.0% 

Aqueous solution of caustic soda (40%) 4.5% 

Gasoline 87.5% 

Other satisfactory fillings which involved 


fewer critical materials than the 

NP or IM 

fillings, but which were never used 

in produc- 

tion, were the following. 


S.O.D. Formula 122i. 2 


Stearic acid 

3.5% 

Rosin 

1.8% 

Cottonseed oil 

3.0% 

Aqueous solution of caustic soda (33%) 3.3% 

Gasoline 

88.4% 

Cellucotton Filling 


Cellucotton chunks 

10-15% 

Gasoline 

85-90% 


Clusters of AN-M69 Bombs. For efficient car¬ 
riage in bombardment aircraft small bombs 
must be carried in some sort of cluster or bomb 
container. During World War II, AN-M69 in¬ 
cendiary bombs were manufactured and sup¬ 
plied to the theaters of operation in the follow¬ 
ing 5 clusters. 

1. AN-M12, 100-lb size, quick-opening cluster, 
consisting of 14 AN-M69 bombs assembled in 
a M4 cluster adapter (Fig. 3) This cluster has 
an actual weight of 105 lb and measures 8.4 in. 
maximum width and 39.3 in. maximum length. 
The size of the cluster is approximately that 



Figure 3. AN-M12, 100-lb size, quick-opening 
cluster of AN-M69 incendiary bombs. AN-M13, 
500-lb quick-opening cluster is similar in con¬ 
struction and appearance. 

of a 100-lb GP bomb, and it will fit on practically 
all 100-lb bomb stations. 

2. AN-M13, 500-lb size quick-opening cluster 


consisting of 60 AN-M69 bombs assembled in a 
M7 cluster adapter.^"^ This cluster has an actual 
weight of 425 lb and measures 17 in. maximum 
width and 58.9 in. maximum length. The size of 
the cluster is somewhat wider than a 500-lb 
GP bomb, but nevertheless it will fit on prac¬ 
tically all 500-lb bomb stations. 

3. E28 (also called M18 or E6R2), 500-lb 
size aimable cluster consisting of 38 AN-M69 
incendiary bombs assembled in a E6R2 cluster 
adapter (Figures 4 and 5).^^’ The actual weight 



Figure 4. E28, 500-lb size aimable cluster of 
AN-M69 incendiary bombs. 

of the cluster is 350 lb and it measures 14.7 in. 
maximum width and 59.0 in. maximum length. 
The size of the cluster is practically the same as 
a 500-lb GP bomb, and it will fit on practically 
all 500-lb bomb stations. This cluster was used 
in the initial incendiary attacks on Japanese 
cities. 

4. E36, 500-lb size aimable cluster consisting 
of 38 AN-M69 incendiary bombs assembled in 
an E21 cluster adapter. This cluster is a varia¬ 
tion of the E28 cluster and its weight and 
dimensions are the same as the E28 cluster. The 
E36 cluster was produced in relatively small 
quantities between production of the E28 and 
M19 clusters. 

5. M19 (E46), 500-lb size aimable cluster 
containing 38 AN-M69 bombs assembled in a 
M23 (E23) cluster adapter (Figure 6). The 
actual weight of the cluster is 425 lb and it 
measures 14.8 in. maximum width and 59.5 in. 
maximum length. The size of the cluster is 
practically the same as a 500-lb GP bomb, and 
it will fit on practically all 500-lb bomb stations. 
This cluster was the principal one used in the 
incendiary attacks on Japanese cities (Figure7). 





14 


INCENDIARY BOMBS AND CLUSTERS 



Figure 5. B29 load of 40 E28 aimable clusters of AN-M69 incendiary bombs. 



Figure 6. M19, 500-lb size, aimable cluster of AN-M69 incendiary bombs. 


Performance Data 

Mode of Functioning. When a cluster of AN- 
M69 bombs is dropped from an airplane the 
following sequence of actions takes place. 

1. After dropping some distance, depending 
on the type of cluster, the cluster breaks open, 
releasing the individual bombs. 

2. The wind catches the tail streamers, pull¬ 
ing them out to their full length, thereby stab¬ 
ilizing the bomb so that it falls nose down. 

3. When the cluster disperses, the bombs are 
armed as the safety plungers are relieved from 
contact with adjacent bombs. 


4. On impact the striker passes through the 
space occupied by the safety plunger before 
arming, and the firing pin strikes the primer 
cap. 

5. The flash from the primer cap ignites the 
spitter fuze. 

6. After 3 to 5 sec delay the spitter fuze 
ignites the booster charge attached to the back 
of the fuze. 

7. The booster charge in turn ignites the 
main ejection-ignition charge contained in the 
two celluloid powder containers. 

8. The explosion of these charges ruptures 
the sealing diaphragm, ejecting the impact 








AX.M69, 6-LB OIL lACEADIARY BOMB 


15 



Figure 7. Salvo of M19 aimable clusters dropped from a B-29 over Yokohama. Photo shows 28 clusters, 
although a full load for a B-29 would be 40 clusters. 


plug, fuel charge, tail cup and streamers, and 
simultaneously igniting the fuel charge. Burn¬ 
ing magnesium particles from the ejection-igni¬ 
tion charge insure ignition of the fuel charge. 

9. The flaming fuel charge in the sock is 
thrown through the air for distances up to 300 
ft until it strikes an obstruction (Figure 8). 
On impact the fuel charge smears over the sur¬ 
face of the object struck, instantly producing 
a mass of flames 6 to 8 ft high. The pattern of 
distribution of the fuel depends on the nature 
and distance of the object struck and on the 
consistency of the fuel. 


10. In the case of bombs containing the WP 
cup, this cup is ruptured when the bomb im¬ 
pacts and upon ejection of the fuel charge the 
phosphorus charge is broken up into many small 
particles. The burning particles of phosphorus 
produce a thick white smoke practically in¬ 
stantaneously. 

Per Cent Functioning. The per cent function¬ 
ing of AN-M69 bombs increased steadily with 
improvements in design of bombs and clusters 
and in production technique during 1943 and 
1944. Table 1 gives some representative figures 
on the performance of bombs in M19 aimable 




16 


INCENDIARY BOMBS AND CLUSTERS 



Figure 8. AN-M69 incendiary bombs, firing at 
workbench target, illustrating horizontal pro¬ 
jection of fuel. 


clusters, dropped at Eglin Field during the 
period October 11, 1944 to February 8, 1945.^" 
These data are not sufficiently extensive to yield 
any reliable correlation with altitude of release 
on opening, even though the single group from 
30,000 ft is the lowest figure. The relatively high 


clusters is somewhat higher than that from 
aimable clusters because of the smaller stress 
on the bombs on release from the cluster and 
because of the greater time of flight available 
for stabilization of the bombs. 

Fuze failures (0.4 per cent) are also negligibly 
small. This satisfactory function is the result 
of many minor improvements in the design and 
production technique of the Ml fuze, and it 
attests to the fundamental soundness of the 
design of this fuze. 

Ballistic Characteristics. A novel feature of 
the AN-M69 incendiary bomb is the cloth 
streamer tail. This type of tail imparts a high 
degree of stability to the bomb and also has 
such a positive drag that on release from a 
cluster the individual bombs are very quickly 
stabilized and slowed to their normal terminal 
velocity. For this reason the striking velocity of 
this bomb is practically uniform at 220-230 ft 
per sec from quick-opening clusters dropped 
from 3,000 ft or higher, or from aimable clusters 
opened at 3,000 ft or higher. This figure has 
been determined both by observations of bombs 


Table 1. Functioning of AN-i\I69 incendiary bombs in i\I19 aimable clusters. 


Altitude of release, ft 

10,000 

10,000 

15,000 

30,000 

15,000 


.Altitude of opening, ft 

3,000 

5,000 

5,000 

5,000 

7,500 


Clusters dropped 

7 

13 

7 

14 

9 

50 

Bombs dropped 

266 

494 

266 

532 

342 

1,900 

Bombs recovered 

261 

473 

247 

504 

325 

1,810 

Bombs functioned O.K. 

254 

450 

241 

474 

314 

1,733 

Number of air bursts 

0 

0 

0 

0 

4 

4 

Number of duds on ground 

7 

23 

6 

30 

7 

73 

Flat landers 

0 

9 

3 

18 

7 

37 

Lightly struck primers 

0 

8 

0 

2 

0 

10 

Fuze failures 

0 

6 

1 

1 

0 

8 

No apparent cause 

7 

0 

2 

9 

0 

18 

Per cent functioning* 

97.3 

95.1 

97.6 

94.0 

96.6 

95.7 


*On recovery basis. 


percentage of flat landers from 30,000 ft is prob¬ 
ably due to tail streamers being torn off as a 
result of the greater velocity of the clusters at 
opening and the resultant greater stress on the 
tail streamers when they come out. The per cent 
of air bursts (0.2 per cent) is of negligible pro¬ 
portions, although this was not true in the 
earlier E28 and E36 clusters, which had ex¬ 
plosive opening mechanisms instead of a me¬ 
chanical opening mechanism. 

The per cent functioning from quick-opening 


in flight and by wind-tunnel measurements. 
If quick-opening clusters are dropped from less 
than 3,000 ft the bombs strike at less than 
220-230 ft per sec, and if aimable clusters are 
opened at less than 3,000 ft the bombs strike 
at more than 220-230 ft per sec. 

The trajectory followed by AN-M69 bombs 
depends strongly on the type of cluster involved 
(Figure 9). When released from quick-opening 
clusters the bombs rapidly lose their forward 
component and soon drop practically vertically. 















AN-M69, 6-LB OIL INCENDIARY BOMB 


17 


ALTITUOE^eet 
IS.OWTi ‘ ■ ' 



NOTE: 

these are true trajectories allowing for 
continuous variations in density of the 

atmosphere.range for any release 

altitude other than 25,000 feet cannot 
be rea'' from these curves 


6-lb, AN-M69 bombs in 
Quick-opening Clusters 

t-lb, AN-M50 bombs in 
Quick-opening Clusters 

lOO-lb IB, AN-M47 

6-lb, AN-M69 bombs in 
MI8 (E6R2)Aimable Clusters 

4-lb, AN-M50 .bombs in 
MI7AIAimable Clusters 

lOO-lb GP, AN-M30 

Jor comparison 

500-lb IB, AN-M76 

500-lb GP , AN-M64 

/or comparison 


Aimable Clusters opened 
at 5000 feet 


SOURCE 


0 12 3 4 5 

: Based on data supplied by the 


10 I 
RANGE, 

Ballistic Research Laboratory, 


Ovals represent plan views 
of ground patterns . 

I 12 13 14 

thousands of feet 

Aberdeen Proving Ground, Aberdeen, Maryland 


Figure 9. Trajectories of AN-M69 incendiary bombs in quick-opening and aimable clusters, together with 
other bombs for comparison. 















































































































































































































18 


INCENDIARY BOMBS AND CLUSTERS 


Therefore, their trail in mils and time of flight 
are quite large compared to large bombs. In 
the case of aimable clusters the intact cluster 
falls essentially the same as a large demolition 
bomb down to the point of separation, where¬ 
upon the individual bombs are released and 
follow a nearly vertical trajectory to the 
ground. A few' illustrative data are showm in 
Table 2. 

Table 2. Ballistic data for clusters of AX-M69 

incendiary bombs * 



AX-M69 

in 

AN-M12 

or 

AN-M13 

quick¬ 

opening 

clusters 

AN-M69 
in M19 
aimable 
cluster 
opening 
at 5,000 
ft 

AX-M69 
in E28 
aimable 
cluster 
opening 
at 5.000 
ft 

AX-M64 
500-lb 
GP bombs 
(for com¬ 
parison) 

Release altitude 

10,000 ft 

Trail in mils 

2,440 

859 


! 

61 

Dropping angle, 
degrees 

8.7 

33.9 


41.4 

Time of flight, 
sec 

54.4 

41.7 


25.7 

Release altitude 

25,000 ft 

Trail in mils 

1,467 

463 

329 

68 

Dropping angle, 
degrees 

7.7 

24.0 

25.4 

28.7 

Time of flight, 
sec 

105.6 

61.9 

54.8 

41.9 


Angle of impact 
from vertical 


Percentage of M69 bombs 
with given impact angle 


0 - 10 ° 

11 - 20 ° 

21-30° 

31-40° 

41-50° 

51-60° 

61-70° 

71-80° 

81-60° 


76 

6 

-) 


While the AN-M69 has a high stability and ex¬ 
cellent reproducibility of trajectory, it is ad¬ 
versely affected by cross winds due to its low 
velocity. 



*For airplane speed of 250 mph. 

The AN-M69 bomb has been showm to have 
the highest flight stability of any small in¬ 
cendiary bomb. This is an interesting result 
since originally the cloth tails wmre adopted as 
a supposedly poor substitute for a metal tail, 
in order to economize on the length of the bomb. 
For a considerable number of E28 aimable 
clusters released at 30,000 ft and opened at 
5,000 ft, the average angle of impact on the 
ground was 13 degrees from vertical. The distri¬ 
bution of impact angles is showm in Table 3. 

Table 3. Impact angles of AX-M69 incendiary bomb 
from E28 aimable clusters. 


Figure 10. Typical dispersion pattern of M19 
aimable cluster of AN-M69 incendiary bombs, re¬ 
leased from 20,000 ft and opened at 5,000 ft. 
Circles indicate bombs and cross indicates center 
of impact. Grid is 100 ft sq. Center of impact was 
1,080 ft behind AN-M64, 500-lb GP bomb. 

Cluster Dispersion Patterns .'^'The 
ground pattern given by the dispersion of a 
cluster of small incendiary bombs is an elon¬ 
gated oval or racetrack-shaped pattern (Figure 
10). In the case of quick-opening clusters the 
pattern is several times as long as it is wide, 
w'hile in the case of aimable clusters the elonga¬ 
tion is not so pronounced. The dispersion pat¬ 
terns for the several clusters of AN-M69 bombs 
are as follow's. 

Dimensions of 
racetrack 
figmre which 
includes 90% 
of the bombs 


Quick-opening clusters (dropped from 
10,000 ft) 

E28 Cluster (dropped from 20,000 ft, 
opened at 5,000 ft) 

M19 Cluster (dropped from 20,000 ft, 
opened at 5,000 ft) 


400 X 1000 ft 
340 X 510 ft 


240 X 360 ft 
































AN-M69, 6-LB OIL INCENDIARY BOMB 


19 


The dispersion pattern is substantially the 
same for 100-lb or 500-lb quick-opening clusters. 
In all these dispersion patterns the distribution 
is fairly uniform throughout most of the pattern 
area with a thinning out at the edges. For this 
latter reason the dimensions of the dispersion 
pattern are specified to contain 90 per cent of 
the bombs. 

Penetrating PoK’er.---^3. 24 , 25 . 2 c, 27 pene¬ 
trating power of the AN-j\I69 incendiary bomb, 
at its normal striking velocity of 220-230 ft 
per sec, can be classed as fair or moderate com¬ 
pared to other incendiary bombs. It will pene¬ 
trate practically all light and medium-weight 
roofs including the following. 

Wood planking, about 1 in. 

Slate on wood battens or wood sheathing. 

Tile on wood battens. 

Hollow tile slabs, 'ZYo-Slo in. thick, with or 
without 2-4-in. cinder concrete for drain¬ 
age. 

Lightweight concrete slabs, 21/2-3^2 in. thick, 
with or without 2-4-in. cinder concrete for 
drainage. 

However, the bomb will not penetrate rein¬ 
forced structural concrete 3 in. or more thick. 
Of the industrial targets encountered in World 
War II approximately 80-85 per cent in Ger¬ 
many and 90-95 per cent in Japan had roofs 
penetrable by AN-M69 bombs. 

Fire Starting Efficiency. The fire starting 
efficiency of small incendiary bombs can be 
evaluated by a variety of methods, which will 
be outlined in somewhat greater detail in Chap¬ 
ter 3. Following are a few examples of the fire 
starting efficiency of the AN-M69 bomb against 
some typical targets. 

1. Factory workbench with a wooden tote- 
box underneath.-* This setup was ignited by the 
fuel charge from an AN-M69 bomb whenever 
the major portion of the fuel charge w'as de¬ 
posited on or near the box. 

2. Stack of wooden packing boxes.-* This 
setup was ignited by the fuel charge from an 
AN-M69 bomb whenever the major portion of 
the fuel charge was deposited on or near it. 

3. German houses at Dugway Proving 
Ground.-*- In the tests on these targets re¬ 
sultant fires were classified as follows. 


Fire 

classification Definition of fire 

A1 Beyond fire-guard control in 0-2 min 

A2 Beyond fii’e-guard control in 2-4 min 

A3 Beyond fire-guard control in 4-6 min 

B Beyond fire-guard control in 6 min or more 

C Nondestructive fire 

The fires resulting from functioning M69 hits 
on German houses were as follows. 

Percentage of fires 


Fire classification 

Inside hits 

Ejection hits 

A1 

16% 

0 

A2 

11% 

0 

A3 

10% 

0 

B 

16% 

11% 

C 

47% 

89% 

4. Japanese 

houses at Dugway Proving 

Ground.**- ***- *^ 

Using the same classification of 

fires as in (3), the fires resulting from function- 

ing M69 hits on Japanese houses 

were as fol- 

lows. 

Percentage of fires 

Fire classification 

Inside hits 

Ejection hits 

A1 

32% 

4% 

A2 

22% 

2% 

A3 

14% 

13% 

B 

13% 

31% 

C 

19% 

50% 


Figure 11 shows the action of the M69 in a 
Japanese-type house similar to the Dugway 
houses. 


For a more extensive discussion of the meth¬ 
ods and results of testing AN-M69 and other in¬ 
cendiary bombs see Chapter 3. The results of 
these tests were used to make preliminary esti¬ 
mates of the quantities of incendiary bombs 
required to destroy Japanese cities.*--**-*^-** 


* Operational Results 

AN-M69 incendiary bombs were used opera¬ 
tionally by the following U.S. Army Air Forces 
and Bomber Commands. 


5th Air Force 
7th Air Foi’ce 


10th Air Force 
12th Air Force 
14th Air Force 
15th Air Force 

XX Bomber 
Command 

XXI Bomber 
Command 


Base 

Southwest 

Pacific 

Central Pacific 


India 

Italy 

China 

Italy 

India and China 


Location of targets 
New Guinea, New 
Britain, etc. 
Ponape, Truk, Mari¬ 
anas, Palau and 
other Pacific Is¬ 
lands 
Burma 

Italy and Germany 
China and Formosa 
Italy and Germany 
China and Japan 


Marianas Is. Japan 




20 


INCENDIARY BOMBS AND CLUSTERS 



Figure 11. Destruction of a Japanese type house by a single AN-M69 incendiary bomb. Pictures were 
taken at 0, 10, 15, and 20 min after firing of bomb. 


The use of this bomb by all these units was of 
minor importance, except that of the XXI 
Bomber Command. However, some incidents 
worthy of note are the burning of Ponape Town 
in February-March 1944 by the 7th Air Force, 
the destruction of supply dumps in Italy in 1943 
by the 12th Air Force, and the burning of 
Changsha in October 1944 by the 14th Air 
Force. 

The chief use of AN-M69 bombs was in the 
great incendiary offensive against the major 


Japanese cities by the XXI Bomber Command 
from the jMarianas Islands bases. The first of 
these attacks was on Nagoya on January 6, 
1945, and the first significant one was the his¬ 
toric attack on Tokyo on March 9, 1945 (Fig¬ 
ures 13, 14). Figure 12 illustrates the burning 
of Toyama, a city of 150,000 population, on 
August 1, 1945, by means of AN-M69 bombs. 
Although a complete review of these attacks is 
beyond the scope of this report, Table 4 sum¬ 
marizes the first 27 attacks on Japanese cities. 




















M69X, 6-LB OIL INCENDIARY BOMB, X-TYPE 


21 


Table 4. Incendiary attacks on Japanese cities. 


City 

Date 

No. of 
B-29’s 
attacking 

Square 

miles 

destroyed* 

Tons 

AN-M69 

IB 

Tons 

AN-M50 

IB 

Tons 

AN-M47 

IB 

Tons 

AN-M76 

IB 

Tons 

M74 

IB 

Tons 
HE & 
Frags 

Total 

tons 

dropped! 

1 

Nagoya 

1 '6/45 

57 

0.2 

138 

0 

0 

0 

0 

12 

150 

Kobe 

2/4/45 

69 

0.1 

167 

0 

0 

0 

0 

14 

i 181 

Tokyo 

2/25/45 

172 

0.7 

437 

0 

0 

0 

0 

44 

481 

Tokyo 

3/9/45 

279 

12.5 

1.624 

0 

129 

0 

0 

0 

1,753 

Nagoya 

3/11/45 

285 

2.0 

1,772 

0 

114 

0 

0 

0 

1,886 

Osaka 

3/13/45 

274 

6.6 

1,782 

0 

56 

0 

0 

0 

1,838 

Kobe 

3/16/45 

306 

2.9 

695 

1,178 

0 

352 

0 

20 

2,245 

Nagoya 

3/18/45 

290 

2.4 

289 

105 

972 

467 

0 

19 

1,852 

Tokyo 

4/13/45 

327 

9.3 

1,929 

0 

226 

0 

0 

0 

2,155 

Kawasaki 

4/15/45 

194 

2.9 

812 

0 

312 

0 

0 

40 

1,164 

Tokyo 

4/15/45 

109 

8.6 

462 

0 

325 

0 

0 

15 

802 

Nagoya 

5/14/45 

472 

3.1 

2,679 

0 

0 

0 

0 

0 

2,679 

N agoya 

5/16/45 

457 

3.8 

81 

3,134 

129 

0 

0 

0 1 

3,344 

Tokyo 

5/23/45 

520\ 

22.lt 

3,004 

45 

789 

0 

0 

0 

3,838 

Tokyo 

5/25/45 

464/ 

1,406 

877 

643 

328 

3 

4 

3,261 

Yokohama 

5/29/45 

464 

6.9 

1,899 

19 

778 

0 

0 

0 

2,696 

Osaka 

6/1/45 

458 

3.3 

743 

627 

1,348 

0 

0 

94 

2,812 

Kobe 

6/5/45 

474 

4.4 

1,004 

860 

1,147 

0 

0 

82 

3,093 

Osaka 

6/7/45 

409 

2.3 § 

574 

0 

1,061 

0 

204 

804 1 

2,643 

Osaka 

6/15/45 

444 

T7§ 

74 

2,375 

514 

0 

0 

0 

2,963 

Kagoshima 

6/17/45 

117 

2.0 

476 

7 

360 

0 

0 1 

0 

843 

Omuta 

6/17/45 

116 

0.1 

393 

0 

407 

0 

0 

0 

800 

Hamamatsu 

6/17/45 

130 

1.3 

523 

7 

419 

0 

0 

0 

949 

Vokkaichi 

6/17/45 

89 

1.2 

208 

18 

356 

0 

0 

b 

582 

Toyohashi 

6/19/45 

136 

1.7 

558 

7 

426 

0 

<-> 

0 i 

991 

Fukuoka 

6/19/45 

221 

1.3 

781 

0 

797 

0 

0 j 

^ i 

1,578 

Shizuoka 

6/19/45 

123 

2.3 

531 

0 

375 

0 

0 

b 

906 

Totals 




25,041 

9,259 

11.683 

1,147 

207 j 

1,148 

48,485 


*These areas are actual built-up areas omitting rivers, canals, parks, wide boulevards, firebreaks, etc. The overall areas, including open spaces, would be 
20% to 40% larger. For e.xample, the overall area destroyed in the Tokyo attack of 3/9/45 was 17 to 18 sq miles. 

fThese are the total tons dropped on or near the target city, but frequently a large percentage of the tonnage given did not actually fall within the built-up 
area of the target city. 

JNo cover available between these two attacks. §Includes a small area destroyed in adjacent .Amagosaki. 


The attacks in this table comprise about one- 
half the incendiary bomb tonnage dropped on 
Japanese cities. It will be noted that the AN- 
M69 bomb was the principal incendiary used, 
with the AN-M47 and AN-M50 bombs follow¬ 
ing in importance. Several issues of Impact 
review the results of the incendiary attacks of 
Japanese cities.^^*’ An analysis of some of 
these attacks is given below in Section 3.6. 


M69X, 6-LB OIL INCENDIARY BOMB, 
X-TYPE 

*^ Introduction 

Development of this bomb was initiated in 
May 1942 by the Standard Oil Development Co. 
under Contract OEMsr-354. The purpose of the 


project was to develop a modification of the 
AN-M69 incendiary bomb embodying a delayed- 
action, anti-personnel element as a deterrent to 
fire-fighters (see Chapter 3). 

Description 

Many of the components of the M69X bomb 
are identical with those in the AN-M69 (Fig¬ 
ures 15 and 16)The principal points of 
difference between the two bombs are; 

1. Gross weight of M69X is 7.1 lb compared 
with 6.2 lb for AN-M69 (or 6.4 lb for AN-M69 
with WP cup). 

2. External appearance of M69X is nearly 
identical with AN-M69, except that the fuze 
hole is moved 2% in. towards the tail in M69X 
to make room for the fragmentation unit, and 
a waterproofing rubber patch covers the out- 































22 


INCENDIARY BOMBS AND CLUSTERS 



Figure 12. Toyama, Japan, burning on the night of August 1, 1945, following an attack by AN-M69 in¬ 
cendiary bombs. This city of 150,000 population was one of the most completely destroyed cities in Japan, 
over 95 per cent. 


side face of the fuze. Otherwise the casing is 
identical with that of the final model AN-M69. 

3. A hexagonal steel liner, 0.059 in. thick, 2 V 2 
in. high, is brazed to the inside of the casing 
below the fuze cup for strengthening. 

4. Fuze cup is made of 11-gauge steel instead 
of 13-gauge steel as in AN-M69, because of 
added strength requirement. Also, fuze cup has 
3 /22-in. hole in bottom for transmission of 
powder flash to the delay fuze of the fragmenta¬ 
tion unit. 


5. Delay fuze unit consisting of one to six ft 
of Ensign-Bickford safety fuze coiled helically 
and housed in a thin steel cup. One end of this 
delay fuze is fitted with a piece of Navy quick- 
match to catch the powder flash, and the other 
end is crimped into a special M106 detonator. 
This type of delay fuze burns at a rate of either 
30 or 60 sec per foot. Delays of approximately 
IV 2 , d, and 6 min are provided in quantities of 
40 per cent, 40 per cent, and 20 per cent, re¬ 
spectively. 



M69X, 6-LB OIL INCENDIARY BOMB, X-TYPE 


23 



Figure 13. Nihonbashi District in Tokyo before incendiary attack. Note tbe intermingling of 10 to 20 
per cent modern concrete buildings with 80 to 90 per cent wooden Japanese type buildings. 


6. HE unit consisting of an HE cup, made of 
13-gauge steel, containing 41/2 oz (130 g) of 
pressed tetryl. This unit is press-fitted in place 
in the nose end of the casing. A rubber gasket 
is compressed in place between the delay fuze 
container and the HE cup, providing moisture- 
proof protection for the delay fuze unit. 

7. Rubber patch cemented to the rubber ring 
on the outside face of the Ml fuze for the mois¬ 
tureproofing. This moistureproofing was found 
necessary due to the hygroscopicity of the black 
powder in the delay fuze. 

8. Gasoline gel filling is 2.0 lb instead of 2.6 lb 
in AN-M69. 

9. WP cup is similar to that of AN-M69, ex¬ 
cept that it is shorter and contains 3 oz of white 
phosphorus instead of 6 oz, as in AN-M69. 

10. Booster charge in Ml fuze is 1.0 g A-4 
powder instead 1 g of 50-50 mixture of A-4 
powder and magnesium powder, to avoid instan¬ 
taneous firing of the HE charge. 

Clusters of M69X Bomb. Only one type of 


cluster of M69X bombs was manufactured and 
supplied to the field: M21(E74), 500-lb size 
aimable cluster containing 38 M69X bombs, as¬ 
sembled in a M23(E23) cluster adapter. This 
cluster is identical in appearance with the M19 
cluster of AN-M69 bombs, but it weighs 465 lb 
due to the greater weight of the M69X bombs. 
These clusters were never used operationally. 

Performance Data 

Mode of Functioning.^' The functioning of 
the M69X bomb is the same as that of the AN- 
M69, with the following additional actions. 

1. The flash from the main ejection-ignition 
charge ignites one end of the delay fuze. 

2. When the ejection-ignition charge ejects 
the fuel charge, the empty bomb case is pro¬ 
pelled in the opposite direction so that the bomb 
case and the fire are usually some distance apart. 

3. After a variable delay of II /2 to 6 oiin the 
delay fuze initiates the detonator, which ex- 




24 


INCENDIARY BOMBS AND CLUSTERS 




Figure 14. Nihonbashi District in Tokyo after attack of March 9, 1945, with AN-M69 incendiary bombs. 
The area in this picture is within one mile of the area shown in Figure 13 and has the same type of con¬ 
struction. Note the gutted shells of modern concrete buildings and complete destruction of the Japanese 
type buildings {Life photograph). 

plodes the tetryl charge. 

4. The explosion of the tetryl charge frag¬ 
ments the entire nose end of the bomb including 
HE cup, fuze cup, fuze, impact diaphragm, and 
the bottom one-third of the casing, producing 
over 400 metal fragments. 

Per Cent Functioning .Table 5 gives 
functioning data observed from 30 M21 aimable 
clusters of M69X bombs dropped at Eglin Field, 

Florida, from altitudes of 12,000 to 30,000 ft, 
opening at 5,000 ft, in January-March 1945. It 
will be noted that 36 out of 71 complete duds 
were due to striking on soft earth, which is no 
fault of the bomb. Later production models of 
M69X bombs showed somewhat better function¬ 
ing than that shown in Table 5. 


Table 5. Functioning of M69X incendiary bombs. 


Number of M69X bombs recovered 


939 

Number functioned properly with respect 

to both 


incendiary and fragmentation actions 


856 

Number of air-burst bombs 


5 

Number of duds on ground 


78 

Analysis of duds on ground 



Complete duds 


71 

Flat landers 

28 


Tails torn off 

4 


Lightly struck primer 

36 


Fuze failures 

3 


Incendiary duds, fragmentation O.K. 


3 

Fragmentation duds, incendiary O.K. 


4 

Total 


78 


Overall per cent functioning (recovery basis) 91.2% 
Overall per cent functioning, eliminating lightly 
struck primers consequent or impact in soft 
earth 94.8% 










M69X, 6-LB OIL INCENDIARY BOMB, X-TYPE 


25 



TAIL STREAMERS 
(FOLDED IN POSITION) 


CHEESECLOTH SOCK 
(ENCLOSING INCENDIARY GEL) 


INCENDIARY GEL FUEL CHARGE 
(2.0 LB.) 


0.2 LB. WHITE PHOSPHORUS CHARGE 
(ENCLOSED IN PLASTIC CUP) 


WATERPROOFING RUBBER PATCH 
OVER Ml FUSE 

Ml FUSE 


WATERPROOFING RUBBER GASKET 

BICKFORD DELAY FUSE 
(0.5 TO 6 MIN. DELAY) 

MI06 DETONATOR WITH IGNITION 
CHARGE 

PRESSED TETRYL EXPLOSIVE 
CHARGE (0.25 LB.) 




Figure 16. Detail of nose end of M69X incendiary 
bomb. 


Figure 15. M69X incendiary bomb. External 
view is practically the same as AN-M69 bombs. 

Ballistic Characteristics ."'’Because 
of the heavier weight the normal striking ve¬ 
locity of the M69X bomb is 240-250 ft per sec, 
i.e., about 20 ft per sec higher than the AN-M69. 
The trajectory of the M21 cluster is similar to 
that of the M19 cluster, but on account of the 
greater weight of the former it has a somewhat 
greater range, about 300 ft when .dropped from 
20,000 ft and opened at 5,000 ft. This would 
mean that from 20,000 ft its trail would be 
about 15 mils less. The M69X bomb is some¬ 
what more stable than the AN-M69 due to its 
greater nose-heaviness. 


Cluster Dispersion.'^’ When dropped 

from 20,000 ft and opened at 5,000 ft, the M21 
cluster gives a dispersion pattern (containing 
90 per cent of bombs) approximately 200x300 
ft, compared with 240x360 ft for the M19 
cluster of AN-M69 bombs. 

Penetrating Power.''’ -‘5- In view of its 
greater weight and greater striking velocity the 
M69X has about 35 per cent greater impact 
energy than the AN-M69. However, this does 
not change the penetration picture greatly, com¬ 
pared to the AN-M69. Both the M69X and the 
AN-M69 will penetrate all types of light roofs, 
but neither will penetrate 3-in., or thicker, 
reinforced structural concrete. There are very 
few intermediate types of roofs penetrable by 













































26 


INCENDIARY BOMBS AND CLUSTERS 


M69X that are not also penetrated by the AN- 
M69. In actual flight tests at Dugway Proving 
Ground on Japanese structures no marked dif¬ 
ference was observed. 

Fire Starting Efficieyicyr Although the 
M69X contains 23 per cent less gasoline gel than 
the AN-M69, it was not possible to detect any 
appreciable difference in the relative fire start¬ 
ing efficiency of these two bombs against typical 
combustible targets. Any location in which an 
AN-M69 fuel charge will start a fire, will also 
be ignited by an M69X fuel charge, although 
sometimes it takes a little longer to reach a 
given stage of development of the fire. 

Frag mentation The explosion of the tetryl 
charge fragments the entire nose end of the 
bomb, including the HE cup, fuze cup, fuze, 
impact diaphragm, and the bottom one-third 
of the casing (Figures 17 and 18). Over 400 



Figure 17. Explosion of M69X incendiary bomb 
lying on top of the ground, showing force of ex¬ 
plosion. 

fragments are produced ranging in size from 
several milligrams up to 2 oz and having ve¬ 
locities up to 4,500 ft per sec. An analysis of 
the fragment coverage showed that a 6-ft man 
at a distance of 10 ft from the bomb would have 
a 22 per cent chance of being hit fatally and an 


additional 22 per cent chance of being injured 
not fatally or a 44 per cent chance of being dis¬ 
abled at least temporarily (Figure 19). In ad¬ 
dition, the shock of the explosion will probably 
incapacitate a man for several minutes even if 
he is not hit (based on the results of tests with 
live goats). However, tests showed that the blast 
of the explosion did not adversely affect fires 
burning 3 ft or more away from the HE unit. 

Moistureyroof Characteristics In order 
to make the M69X moistureproof independently 
of its shipping container, the Ml fuze and HE- 
delay fuze assembly must be especially water¬ 
proofed. 

The Ml fuze is waterproofed by the use of a 
vulcanized Neoprene type GN patch 1%-!^. di¬ 
ameter and 0.020 in. thick, cemented to a 
neoprene type GN ring 3/16 in. wide, 1 17/32 
in. OD and 0.015 in. thick, which is vulcanized 
to the casing around the hole. 

The HE-delay fuze assembly is waterproofed 
by the use of a soft vulcanized Neoprene type 
GN rectangular gasket, 3/32 in. thick, 14 to % 
in. wide, placed under the lip of the delay fuze 
cup so that the leading edge of the HE cup rests 
against the gasket as the HE cup is pressed 
flush with the end of the casing. 

Both the Ml fuze and HE-delay fuze assembly 
were subjected to a 24-hr submergence test 
under 6 ft of water and a 7-day storage test at 
100 per cent humidity with cyclical tempera¬ 
tures varying every 12 hr from 70 to 125 F. The 
following results were observed. 

1. Ml fuze showed 97 per cent performance 
out of 266 tested in the submergence test and 
97.7 per cent performance out of 87 tested in 
the storage test. 

2. HE-delay fuze assembly showed 98.3 per 
cent performance out of 120 tested in the sub¬ 
mergence test and 100 per cent performance 
out of 35 tested in the storage test. 


Final Status 

Production of M69X bombs in M21 clusters 
was begun in March 1945, and clusters reached 
operational bases in the Marianas Islands in 
July 1945, but there is no record of their ever 
having been used operationally. This bomb 


Hjiy i 




TTv 








AIMABLE CLUSTERS FOR AN-M69 TYPE BOMBS 


27 



Ln.vt. j 


Figure 18. Fragments recovered from explosion of M69X incendiary bomb. 


would undoubtedly have been more effective, 
possibly twice as effective, as the AN-M69 bomb 
for incendiary attacks on Japanese cities, 

AIMABLE CLUSTERS FOR AN-M69 
TYPE BOMBS 

Introduction 

Aimable or projectile clusters of incendiary 
bombs, which drop as a unit to a predetermined 
height where they are opened by a mechanical 
time fuze, were first developed and used by the 


Germans in 1941. The idea was later adopted 
by the British (1942) and still later by the 
United States (1943). The first United States 
aimable cluster of AN-M69 bombs was the E28 
cluster, also called M18 or E6R2, developed by 
the Chemical Warfare Service in 1943. This 
cluster had several disadvantages: (1) its trail 
was larger than desirable, (2) its flight char¬ 
acteristics were not reproducible, (3) it pro¬ 
duced about 3 per cent of air-burst bombs due 
to the shock of opening, and (4) about 5 per 
cent of the clusters failed to open due to failures 
of the single mechanical time fuze. The E28 
cluster is shown in Figure 20. 




28 


INCENDIARY BOMBS AND CLUSTERS 



Figure 19. Anti-personnel effect of fragments from explosion of M69X incendiary bomb. 


EI8 Aimable Cluster 

In order to overcome the disadvantage of the 
E28 cluster, the development of the E18 aimable 
clusters was begun in January 1944 by the 
Standard Oil Development Co. under Contract 
OEMsr-354. The E18 cluster (also called Cl 
cluster) was 14.4 in. diameter and 69.0 in. in 
length, weighed 425 lb gross and contained 45 
AN-M69 bombs, compared to 38 in the E28 
cluster (Figure 20). The principal components 
of the E18 cluster are as follows: (1) hemi¬ 


spherical nose fairing of sheet steel, (2) two 
hemicylindrical cover sheets, (3) top suspension 
bar, (4) bottom bar, and (5) tail assembly, in¬ 
cluding fairing, box-type tail fins, cylindrical 
tail shroud and two tail fuze adapters. The 
method of opening was by Primacord bursters 
similar to the E28 cluster. 

In order to produce a well-streamlined cluster, 
it was believed necessary to increase the length 
from the standard 59 in. for 500-lb size bombs 
and clusters to 69 in., which was suitable for 
nearly all airplanes until the advent of the B-29 










































AIMABLE CLUSTERS EOR AN-M69 TYPE BOMBS 


29 



Figure 20. Experimental models of aimable clusters of AN-M69 incendiary bombs. Left to right, British 
No. 20 cluster, E18 cluster, and E28 cluster. 





























30 


INCENDIARY BOMBS AND CLUSTERS 


and B-32. The resulting cluster proved to be 
ballistically superior, but the excessive length 
prevented efficient loading on 500-lb bomb sta¬ 
tions in B-29 and B-32 airplanes. For this 
reason the E18 cluster was never standardized 
or produced. 

For comparative purposes some British No. 
20 clusters were made and tested in parallel 
with the E18 and E28 clusters (Figure 20). 
This cluster was 18.0 in. in diameter and 67.3 in. 
in length, weighed 450 lb gross, and contained 
62 AN-M69 bombs. A major difference from the 
E18 and E28 clusters was the method of open¬ 
ing, which was of the mechanical type instead 
of the explosive type. The British No. 20 cluster 
was really of the 1,000-lb size and had to be 
restricted to 1,000-lb bomb stations in loading 
on airplanes. 


Table 6. Comparative data on aimable clusters. 



E2S 

E18 

British 
No. 20 

Cluster weight, lb 

350 

425 

450 

Cluster diameter, in. 

14.2 

14.4 

18.0 

Cluster length, in. 

59.4 

69.0 

67.3 

No. of AN-M69 bombs in cluster 

38 

45 

62 

Terminal velocity, ft/sec 

675 

1,000 

515 

Trail behind AN-AI64, ft* 

2,550 

335 

2,855 

Trail angle, mils* 

179 

135 

189 

Circular probable error, mils* 

30 

15 

50-75 

Cluster pattern, ft 

350x450 

300x450 

300x300 

AN-M69 bomb performance* 

% Air-burst bombs 

2.4 

1.0 

0 

% Tails torn off 

1.7 

6.4 

1.0 

% Flat landers, other causes 

2.8 

1.6 

2.0 

% Fuze failures 

1.5 

0 

0 


*For release from 30,000 ft, opening at 5,000 ft, and true airspeed of 250 
miles per hr for dropping airplane. 


Table 6 gives some comparative data on the 
E28, E18, and British No. 20 clusters."^® These 
data lead to the following conclusions: 

1. The E18 cluster has excellent range, re¬ 
producibility of trajectory, and other desirable 
ballistic characteristics. In fact, its range is 
nearly identical with that of the AN-M64, 500-lb 
GP bomb. 

2. The British No. 20 has poor ballistic char¬ 
acteristics. 

3. The E18 cluster causes an excessive num¬ 
ber of AN-M69 tails to be torn off, owing 
obviously to the high velocity of the cluster at 
time of opening. 

4. The British No. 20 cluster causes no air- 


burst bombs, probably because of the mechani¬ 
cal type of opening instead of the explosive type 
of opening. 


i *-3 Aimable Cluster 

On the basis of these conclusions the Chemi¬ 
cal Warfare Service developed a new aimable 
cluster, the M19 (E46), combining the best qual¬ 
ities of the E18 and British No. 20 clusters, 
and retaining the 59-in. standard length for 
500-lb size bombs (Figures 6 and 
.51, .52, .-..3 ]y[]i 9 cluster had a blunt rounded 



Figure 21. Detail of tail end of M19 aimable 
cluster showing twin tail fuzes and tail shroud 
construction. For overall external view of this 
cluster see Figure 6. 

nose fairing, a streamlined tail with shroud and 
twin tail fuzes similar to the E18, and a me¬ 
chanical type opening which was simpler than 
the British No. 20 mechanism. This produced a 
cluster which still had a somewhat undesirably 
high trail, but its trajectory was very repro¬ 
ducible. The cluster released the bombs with a 
minimum of air bursts and tail damage, and the 
twin tail fuzes insured practically 100 per cent 
functioning of the clusters. Figure 10 shows the 
dispersion pattern of this cluster when dropped 
from 20,000 ft and opened at 5,000 ft. The 
M19(E46) cluster was produced in large quan¬ 
tities and used extensively in bombing Japan 
in 1945. 







(Tail retracted) 


AIMABLE CLUSTERS FOR AN.M69 TYPE BOMBS 


31 




FOLDED 
TAIL STREAMERS 



TETRYL PELLETS 

POWDER PROPELLANT 
CHARGE IN VISCOSE TUBE “ 

OIL-PROOF PAPER SEAL- 
FUZE RETAINING SCREW PLUG- 


SOLID HYDROCARBON CORE 

LB. MAGNESIUM ALLOY ^ 
PERMANENT MOLD CASTING 


PERFORATED STEEL JACKET- 


FM MIXTURE 


NOSE TO JACKET ARC-WELD' 

STEEL NOSE 
HARDWOOD BACKING PLUG 
STEEL FAIRING CUP 




TAIL CHAMBER FOR 
WHITE PHOSPHORUS 


TAIL BURSTER ASSEMBLY 
SCREW PLUG 


tail RETAINING SCREWS 

LEAD GASKET 
KEYWAY 

SAFETY PLUNGER 
RUBBER HOUSING SEAL 
INERTIA FUZE 


i'lvV 



# 



BOMB BODY 



1C 


NOSE TO CUP SPOT-WELD 


Figure 22. E19 incendiary bomb, external and phantom views 






























































































































































































































































































































32 


INCENDIARY BOMBS AND CLUSTERS 


E19, 11-LB MAGNESIUM INCENDIARY 
BOMB 

Introduction 

The E19 bomb was originally conceived as a 
more potent fire-raiser than the AN-M50 for 
use on German domestic construction. Later, 
with the development of aimable clusters, its 
possible use on factory targets in precision 
bombing was considered. The E19 was a bomb 
of the same external dimensions as the AN-M69 
bomb, but heavier, and had a terminal velocity 
of about 650 ft per sec, so that its penetrating 
power was adequate for either use. As compared 
to existing small incendiary bombs, the E19 
has higher penetrating power, in addition to 
the special features, in that the bomb is pro¬ 
pelled to a favorable site after impact, and that 
the flame resists the action of ordinary ex¬ 
tinguishers and is screened from fire fighters 
by an obscuring phosphorus smoke. 

Description 

The E19 is identical in outside dimensions to 
the AN-M69, namely 19V2 in. long by 2% in. 
across the hexagonal flats (Figure 22).^-^’^^ It 
consists essentially of a magnesium body en¬ 
closed in a perforated steel sleeve welded to a 
steel nose-piece, filled with a mixture of several 
incendiary materials, and fitted with a spring- 
out metal tail. The gross weight is 11 lb. 

The bomb is a thin-walled magnesium shell 
encased in a perforated steel sleeve welded to 
a steel nose-piece. The principal incendiary 
filling has the following composition: 

Flake aluminum 14.8% Sulfur 1.6% 

Sodium nitrate 14.8% Motor oil 7.1% 

Barium nitrate 11.7% Thermite 50.0% 

For a further description of this mixture see 
Section 8.7. This mixture is loaded under com¬ 
pression into an annulus surrounding a case of 
solid hydrocarbon wax. A perforated steel dia¬ 
phragm holds both fillings in place. The incen¬ 
diary filling is satisfactorily ignited under light 
confinement by a flash of black powder from 
the fuze; and no first-fire mixture is required. 
The mixture of finely divided metal and oxidiz¬ 


ing agents burns with an intense heat sufficient 
to ignite the magnesium casing and to crack the 
hydrocarbon wax to volatile gases. The result is 
a combined jet and magnesium bomb. The per¬ 
forated diaphragm or propellant cup keeps the 
filling in place and promotes the development 
of an internal pressure sufficient to force jets 
of flame to issue from successive perforations 
in the steel sleeve. Thus, intensely hot flames, in 
a series of radial jets, issue from the bomb over 
a period of 3 to 4 min, and a residual flame and 
heat effect from the more slowly burning mag¬ 
nesium metal persists much longer. The total 
heat release is greater than that of the M50 
bomb on the basis of either cluster volum.e or 
weight and about equals that of the M69 bomb 
on a cluster basis.5*^’ 

The fuze is very similar to the Ml fuze used 
in the AN-M69 bomb. The fuze is waterproofed 
by a rubber sleeve enclosing the safety plunger. 

The tail contains a charge of phosphorus 
which is dispersed by a central burster. A part¬ 
ing charge separates the tail and the main 
bomb body after a 3-sec delay. 

The E19 bomb is loaded in the same clusters 
as the AN-M69 bomb, but since the E19 is 
heavier than the M69, the nose and tail weights 
of the E23 cluster adapter can be omitted. 

^ Performance Data 

The action of the E19 is illustrated in Figure 
23. After impact there is a 3-sec delay train in 
the fuze similar to the action of the M69. After 
coming to rest an igniter charge of 0.6 g of 
black powder leads the flash to a separating 
charge of 7 to 8 g of black powder, which then 
shears off the tail and, at the same time, ignites 
the bomb and kicks it in the opposite direction 
with sufficient force to cause it to come to rest 
against a wall or other obstacle. The bomb thus 
has an advantageous feature of tending to come 
to rest in a site favorable for starting a fire. 
The tail assembly comprises a streamlined 
canister loaded with phosphorus, with an ex¬ 
tensible extruded magnesium fin-tail making 
for economy of load in the cluster. The canister 
carries an explosive charge that operates a 
few seconds after the tail has been separated 
from the body of the bomb. 



E9, 40.LB OIL INCENDIARY BOMB 


33 



Figure 23. Action of E19 incendiary bomb. Note 
the jet-like flames issuing through the perforated 
bomb case in the middle view. 


Thus, in the normal case the tail explodes at 
some distance from the body and produces an 
obscuring screen offering a considerable de¬ 
terrent to the fire-fighter. In addition, the sud¬ 
den release of a shower of burning phosphorus 
produces an explosion wave capable of shatter¬ 
ing windows and blowing out doors and frames. 
The burning phosphorus tends to ignite any 
readily inflammable material in the area with 
consequent increase in room temperature and 
accentuation of the action of the bomb proper. 


Penetration tests with bombs fired at ve¬ 
locities up to 650 ft per sec indicate that in the 
majority of instances the tail stays in place 
even when the bomb penetrates a thick con¬ 
crete roof or suffers abrupt setback on a con¬ 
crete slab. It will penetrate up to 6 in. of singly 
reinforced concrete slab, unless it hits directly 
over a reinforcing rod. In some instances of 
severe punishment, for example in a glancing 
hit, the tail may be ripped off the body on impact 
and prior to the operation of the separating 
charge. However, the bomb is ignited by the 
fuze even though the tail is lost on impact. 

All of the dropping tests indicate that the 
bomb has excellent ballistics. Its center of grav¬ 
ity is 81/^6 in. from the nose, while its metacen¬ 
ter is 9 Vs in. In the event that a lower penetra¬ 
tion is required, the striking velocity can be 
controlled by the addition of three tail stream¬ 
ers of Class A binding tape, each % in. wide, 
looped over the struts of the sliding tail vane 
and fastened with wire staples. The foot 
streamers of this material, which is much more 
effective than sheeting, reduce the terminal 
velocity to approximately 500 ft per sec when 
the bombs are released from the cluster at a 
level above 8,000 ft. The ends of the streamers 
are dipped into heavy lacquer to prevent them 
from fraying. 


^ Final Status 

Although development of the E19 was satis¬ 
factorily completed, the decision was reached 
not to put the bomb in production, because of 
the absence of evidence that enough targets 
existed on which it would show performance 
superior to existing bombs. 

1 E9, 40-LB OIL INCENDIARY BOMB 

Introduction 

Development of this bomb was initiated in 
February 1943 by The Texas Co. under Con¬ 
tract OEMsr-898. The request for a bomb of 
this intermediate size came from the Chemical 
Officer of the Eighth Air Force in England. 

The basic conception was to develop a me- 



























34 


INCENDIARY BOMBS AND CLUSTERS 


dium-size bomb which would have good ballis¬ 
tics, would penetrate a substantial target, and 
carry the maximum amount of incendiary fuel. 
The bomb was intended for use in high-altitude 
precision bombing, and was to be carried in a 



Figure 24. E9 incendiary bomb, external and 
cutaway views. Cutaway view does not have gel 
filling, white phosphorus, ejection charge, burster 
charge, or HE charge in place; otherwise homb 
is complete. 


cluster that would utilize fully the space avail¬ 
able on the 500-lb bomb station of American 
planes. It was planned to incorporate a charge 
of white phosphorus in addition to the incen¬ 
diary gel, and to include a high-explosive ele¬ 
ment that would cause fragmentation of the 
nose. Thus the bomb would be a highly aimable 
all-purpose medium-size bomb. It would have 



Figure 25. Detail of nose end of E9 incendiary 
bomb. 


far greater penetrating power than the M50 
4-lb magnesium bomb, the M69 6-lb oil bomb, or 
the M47 100-lb oil bomb, and would contain a 
substantial amount of incendiary fuel. 

A preliminary design study attempted to 
meet the required properties in a bursting-type 
bomb. Concurrently the Chemical Warfare 
Service had been designing a tail-ejection bomb 
in this same size range and with some of the 
same features. On March 31, 1943, at a confer¬ 
ence at Edgewood Arsenal, the two designs 
were amalgamated with the CWS tail-ejection 
model predominating in the combined model. 
This project was then turned over to The Texas 
Co. for development. A principal subcontractor 
under The Texas Co. was the Foster-Wheeler 
Corp., which had the primary responsibility for 
the mechanical design. 












E9, 40-LB OIL INCENDIARY BOMB 


35 


Description 

Bt'ief Descri'ption. As finally produced in 
limited procurement for test purposes the E9 
bomb consisted of a heavy steel nose, an hexa¬ 
gonal steel case, and an extensible metal tail 
(Figures 24 and 25). The overall dimensions 
were such that fourteen bombs, in two banks 
of seven, formed a cluster which utilized fully 
the space available on a 500-lb bomb station. 
Attached to the nose was an arming vane which 
permitted an out-of-line detonator to slip into 
position only after the bomb was separated 
from the cluster and had fallen away from the 
airplane. Contained in the nose were a delay 
train and blasting cap and a high-explosive 
charge. The heavy nose shell screwed into a 
forged steel base plate, which carried the out- 
of-line detonator and the safety pin that pre¬ 
vented arming of the bombs while clustered. 
Attached to the other side of the base plate 
were two steel domes and the steel case which 
contained the incendiary fuel. The inner dome 
contained the ejection charge, and the space 
between the two held the white phosphorus. 
The far end of the hexagonal case was rounded, 
and attached to it was a thin conical section 
which carried the extensible metal tail. 

Pertinent data on the final design are as fol- 


lows. 


Diameter 

5 in. 

Length, tail collapsed 

29%,! in. 

Length, tail extended 

33% in. 

Weight empty 

29.7 lb 

Weight loaded 

40.5 lb 

Weight of incendiary 


(13% Napalm-gasoline) 

9.5 lb 

Weight of WP 

0.8 lb 

Weight of tetrytol 

0.65 lb 

Weight of booster charge 


A-4 black powder 

2g 

Composition of ejection charge 


75-mm FMH smokeless 


Cannon powder 

20 g 

A-4 black powder 

6g 

Oiled magnesium powder 

9 g 

Center of gravity, distance from nose 

11.1 in. 


Details of Design. 1. Nose. The nose of the 
E9 bomb was a steel forging, shaped into an 
ogive to provide maximum thickness at the 
point where impact occurred. A %-in. hole pro¬ 
vided for the shaft of the vane arming fuze 
mechanism to pass through the nose. Attached 


to the outer surface was a guard ring which 
protected the arming vane. There were also two 
sockets for the special wrench with which the 
nose was screwed onto the base plate. 

2 . Base plate. This was a steel forging, which 
carried the out-of-line detonator and the safety 
plunger. Through it passed the striker pin. 

3. HE cup. A spun steel cup, designed to fit 
snugly into the nose, contained the tetrytol. 

4. Delay fuze. A coil of Bickford fuze, con¬ 
tained in a shallow metal cup, fitted inside the 
nose and into a recess in the base plate. Burn¬ 
ing of the delay was initiated by the black- 
powder ejection charge in the dome. 

5. Out-of-line detonator. This was a spring- 
loaded element which slid into position after 
the striker pin had withdrawn sufficiently fol¬ 
lowing rotation of the arming vane. 

6 . Safety pin. A spring-loaded pin was held 
in position to prevent retraction of the striker 
pin when the bombs were clustered. When the 
cluster opened and the bombs separated, the 
safety pin was thrown out of the way. 

7. Booster charge. This was contained in a 
cellophane cup, in line with the primer and in 
contact with the black powder in the dome. Its 
function was to ensure rapid and complete 
ignition of the black powder. 

8 . Powder dome. This was a light steel dome, 
brazed to the base plate and scored to facilitate 
rupture of the dome near its base. 

9. WP dome. The white phosphorus was con¬ 
tained in the space between the inner and outer 
domes. 

10. Casing. The casing was of steel l^-in. 
thick, formed from tubing which was left 
round at both ends for attachment to the base 
plate and tail cone. The intermediate portion 
was hexagonal, which facilitated clustering and 
provided a snug fit to hold the safety pin in 
place, and also increased the fuel capacity by 
about 3 per cent. 

11. Tail cone. This was a light-gauge tapered 
shell which was blown off when the bomb func¬ 
tioned. 

12 . Extensible tail. A finned metal tail was 
attached to a post which seated into a recess 
in the tail cone. By means of a coiled spring the 
tail was extended when the bombs broke out 
of the cluster. 




36 


INCENDIARY BOMBS AND CLUSTERS 


Fillings for Bomb. The only fillings that could 
be used were those capable of being introduced 
through the small hole in the tail cone. Gasoline 
gel containing thirteen per cent Napalm was 
used in the bombs made for test purposes. An 
extensive series of tests was conducted to de¬ 
termine the optimum fuel for the E9 bomb. 
After small-scale laboratory tests had estab¬ 
lished a preliminary order of merit, a full- 
scale field test mortar was used for evalu¬ 
ating the fillings. The mortar had the same 
capacities as the regular bomb and utilized the 
same rupturable domes and cones. A concrete 
block framework was erected 36 ft from the 
mortar. Sound i/4-in. plywood was mounted on 
the framework for each shot. A fuel was rated 
according to the percentage of the plywood tar¬ 
get burned within a ten-minute period. 

The following fuels are recommended in the 
order of preference. 

1. 12% cellucotton in 5 cylindrical wads, 42 

in. long and 3 in. in diameter. 

58.5% turpentine. 

19.5% furfural extract from lube oil. 

10% magnesium, type B, 40/100 mesh. 

2. 15% cellucotton in 5 cylindrical wads, 42 

in. long and 3 in. in diameter. 

85% turpentine 

3. 12% cellucotton in 5 cylindrical wads, 42 

in. long and 3 in. in diameter. 

58.5% turpentine. 

19.5% furfural extract from lube oil. 

10% ammonium nitrate. 

4. 4% polyisobutyl methacrylate polymer 

containing 0.3% methacrylic acid. 

1% 40% aqueous sodium hydroxide. 

20 fo toluene. 

75% gasoline. 

5. 13% Napalm thickener, type B. 

87% gasoline. 

It can be noted that a wadding or solid type 
of filling produced the best results. The use of 
this material, however, would involve a re¬ 
design whereby a full 5-in. diameter opening 
could be employed. The design of a satisfac¬ 
torily strong and leak-proof connection or seal 
of this size was not worked out during this 
investigation. It is believed, however, that this 
type of filling would offer more promise than 
the standard types of thickened gasoline. 


E53 Cluster of E9 Bombs 

The E9 bomb was originally intended for use 
in a quick-opening cluster of the 500-lb size. 
When the Air Forces ruled against the use of 
quick-opening clusters for release from planes 
flying in large formations, because of the 
danger from slowly falling metal components, 
there was a general trend toward delayed- 
opening aimable clusters. These require a nose 
fairing and a tail to give good ballistics. Since 
there was no room to add these components to 
the cluster of E9 bombs it became necessary to 
devise an adapter which would open quickly and 
consist of parts that would fall nearly as rapidly 
as the bombs. This was accomplished by using 
a small number of strong streamlined com¬ 
ponents and by replacing the conventional steel 
straps with low air-drag cables attached to the 
main cluster bar. This adapter was known as 
the E26 cluster adapter, and the complete 
cluster of 14 E9 bombs was designated the E53 
cluster. 

The essential features of the E26 cluster 
adapter and E53 cluster are illustrated in Fig¬ 
ures 26 and 27. The principal components are 
briefly described as follows. 



Figure 26. E53, 500-lb size, quick-opening cluster 
of E9 incendiary bombs. 


1. Main cluster bar. This is a hollow steel 
tube 2 in. in diameter, with a heavy rounded 
nose and an extensible finned metal tail. It con¬ 
tains the mechanism which opens the cluster, 
and permanently attached to it are the four 
steel cables that hold the bombs until the cluster 
opens. It is fitted with a hoisting lug and with 


















E9, 40-LB OIL INCENDIARY BOMB 


37 



Figure 27. Detail of nose end of E53 cluster. 


carrying lugs for attachment to a standard 
bomb shackle. 

2. Stiffening bars. Two lengths of 1-in. pipe, 
weighted at one end, and provided with light 
metal tails, are placed 120 degrees from each 
other and from the main cluster bar. These 
serve to hold all bombs firmly in position when 
the cables are tightened. 

3. Javelins. These are three slender steel rods 
which serve to prevent the central bombs from 
sliding forward or backward in relation to the 
outer bombs. One end of each is enlarged and 
the other end has a flat disk which engages the 
tails of the rear bombs in the cluster. The three 
javelins are placed around the two central 
bombs at intervals of 120 degrees. 

4. Cables. These are 5/32-in. woven steel air¬ 
plane cables, fitted with threaded connectors 
by which they can be drawn up tightly against 
the bombs. One end is permanently locked into 
position inside the main cluster bar. The other 
end is held by a latch until released by the 
functioning of the cluster opening mechanism. 

5. Cluster release mechanism. In the nose of 
the main cluster bar is a fuze, consisting of a 
cocked firing pin, a li/4-sec delay pellet and a 
charge of black powder contained in a steel 
cylinder. The firing pin is prevented from mov¬ 
ing by a rotating safety pin which cannot turn 
until the arming wire pulls out as the cluster 
leaves the airplane. Pressure developed by the 
burning of the black powder is applied to a 


piston. Beyond the piston is a steel rod carrying 
4 integral steel latches which hold the free ends 
of the cables. When the powder burns, the 
moving piston causes the rod to slide within 
the main cluster bar, releasing the free ends of 
the cables and opening the cluster. The four 
cables then fall with the main bar to which 
they were attached. 

The E26 adapter weighs 58 lb, and the com¬ 
plete E53 cluster of 14 E9 bombs weighs 618 lb. 
It is noteworthy that this cluster adapter, 
weighing less than 10 per cent of the total 
weight of the cluster, was strong enough to 
meet the latest requirements for strength of 
clusters as prescribed by the Joint Aircraft 
Committee in the spring of 1945. New clusters 
were required to withstand a stress equal to 
18 g (18 times the force of gravity) in a ver¬ 
tical direction, 7.5 g fore and aft, and 3 g side¬ 
ways. None of the clusters in common use by 
the U.S. Air Forces at the end of World War II 
could meet these requirements, despite the fact 
that the relative weight of their adapters was 
in general much greater than 10 per cent of the 
total. The novel features of the E26 cluster 
adapter should be kept in mind in future work 
on bomb clusters. 


Performance Data 

Mode of Functioning. When an E53 cluster 
is dropped the following sequence of actions 
takes place: 

As the cluster leaves the bomb bay the arming 
wire pulls out of the safety pin, permitting it to 
rotate and free the spring-loaded striker pin 
of the cluster fuze. The striker pin moves for¬ 
ward, firing a primer which in turn ignites a 
delay composition that burns through in about 
11/2 sec. A small charge of black powder then is 
ignited and moves a piston and the steel rod 
which carries the four latches that have locked 
the free ends of the cables in place. When these 
are released the cluster disintegrates and the 
14 bombs are free to fall individually. The ex¬ 
tensible tail on the main cluster bar springs out 
and the bar, with the four steel cables attached 
to it, falls rapidly, as do all other members of 
the adapter. 



38 


INCENDIARY BOMBS AND CLUSTERS 


As the bombs separate, each safety pin is 
thrown out and the propeller arming vane ro¬ 
tates rapidly. This action draws the firing 
pin toward the nose end of the bomb and soon 
permits the out-of-line detonator to slide into 
the firing position. When the bomb strikes the 
target the firing pin is driven back into the 
primer-detonator. This fires the booster charge 
which ignites the black powder ejection charge. 
The domes are ruptured and the pressure causes 
the tail cone and bomb tail cone and bomb tail 
to part from the case, ejecting the gel and 
white phosphorus. The Bickford delay fuze 
starts to burn and after approximately 2 min 
the high-explosive charge shatters the nose and 
part of the casing. 

Per Cent Functionmg. Ten clusters of bombs 
with inert filling in the HE cup were dropped 
from 20,000 ft onto the clay flats at Dugway 
Proving Ground. The bombs penetrated from 
8 to 14 ft into the clay, and no gel was observed 
to emerge above the ground level. By probing, 
it was found that several of the bombs had 
functioned. However, two bombs were found 
which had malfunctioned because of deforma¬ 
tion of the firing pin. 

Fifteen clusters of bombs complete with live 
HE in the nose were dropped from 20,000 ft 
onto the industrial target building at Eglin 
Field, Florida. Several complete duds were 
found, and in a few instances instantaneous 
detonation of the high-explosive charge oc¬ 
curred when the bomb hit the target area. 

It appears that some further development 
would be required to insure a satisfactorily 
high percentage of functioning. Minor changes 
would be needed to strengthen the firing pin 
assembly and to prevent the arming vane from 
bending without transmitting the required 
thrust to the firing pin. Further study to pre¬ 
vent premature detonation of the HE charge 
is also indicated. It is believed that the pressure 
built up in the inner dome causes a flash which 
sometimes bypasses the Bickford fuze and sets 
off the blasting cap. The fact that completely 
satisfactory functioning occurred in some in¬ 
stances suggests that the troubles encountered 
could be overcome by minor changes in the con¬ 
struction of the bomb. 

Ballistic Characteristics. When properly 


launched in high-level flight, the E9 bomb ex¬ 
hibited excellent ballistic properties. The trail 
angle was small compared to most other in¬ 
cendiary bombs and was well within the scope 
of the standard bombsights, being almost ex¬ 
actly the same as for the M38A2 practice bomb. 
It was apparent that the design was successful 
in yielding a bomb that was suitable for pre¬ 
cision bombing from high altitude. When re¬ 
leased from the cluster, some of the bombs were 
thrown out at random and exhibited a certain 
amount of preliminary tumbling and yawing 
before assuming true flight. This resulted in a 
separation of the bombs and caused some of 
them to fall a considerable distance behind the 
others. It is believed that if a suitable bomb 
rack were available to release all bombs indi¬ 
vidually in true flight the ballistic character¬ 
istics would leave little to be desired. 

Cluster Dispersion Patterns. Ten E53 clus¬ 
ters were dropped from 20,000 ft onto the clay 
flats at Dugway Proving Ground. One cluster 
did not open. Of the 14 bombs in a cluster, be¬ 
tween 8 and 12 fell into an area the width of 
which varied from 100 yd to 150 yd and the 
length varied from 100 yd to 375 yd. From one 
to three bombs usually landed about 600 yd to 
the rear, and in three instances from one to 
three additional bombs landed approximately 
1,200 yd to the rear. When the impact patterns 
of these clusters were superimposed upon a line 
through the leading bomb in each cluster, it 
was found that 55 per cent of the bombs fell 
within an area measuring 200x200 yd, 80 per 
cent were within an area 200 yd wide by 775 
yd long (Figure 28). 

The leading bombs in each cluster fell near 
the M38A2 practice bomb, and most of the 
bombs were consistently grouped within a 
reasonable distance of the practice bomb. This 
is evidence that the E9 bomb, when properly 
launched, has excellent ballistics; and also in¬ 
dicates a high degree of aimability for the 
cluster, despite the fact that a few of the bombs 
usually fell far to the rear. Clusters of other in¬ 
cendiary bombs frequently gave tighter and 
more uniform patterns, but their centers of 
impact varied widely with respect to the aiming 
point where the M38A2 bomb landed. When 
considered in terms of a stick of clusters from 



E9, 40-LB OIL INCENDIARY BOMB 


39 


LINE OF FLIGHT 


Aooo yds 

Jl 125 yds 

J.250 yds 
-^225 yds 

. (1/2 clu 

i-yO o— 

ster) 

1 

-fls- 

Q 

-A- 

o 

0 

A < 
o ^ 

o 8 

O 6> < 

)0 0 
o ° 

-tJ— 

0 d) 

^125 yde 

^250 yd3 
^1250 yds 
^500 ydd 

0 o 

. o 

. (7 Bombs 
_C 

O 

O 

) 

!_ 

< 

o 

o 

- 

) o° 

o 


c 

) 

<xPc 
. o c 

,0,0 o£ 

3 O 

n vS' VS 

D ® 


900 800 700 600 500 400 300 200 100 0 

YARDS 

O^E-9 BOMB (g) = M-38 BOMB A=CLUSTER STIFFENER 


Figure 28. Superposition of impact patterns of nine E53 clusters of E9 incendiary bombs dropped from 
20,000 ft. 


a single plane, or many clusters from a group 
of planes, the dispersion pattern of the E53 
cluster appeared satisfactory. The high in¬ 
trinsic aimability of the E9 bomb increases the 
probability that some bombs will hit a specific 
target, even though a few will trail consider¬ 
ably. 

Release from Fighter Planes. E53 clusters 
were released from P-51 fighter planes at 350 
mph at an angle of 30 degrees from 3,000 ft 
elevation in a glide bombing attack. All the 
bombs hit close to the target in a pattern about 
200 ft by 300 ft. The E53 cluster is probably 
the only incendiary bomb cluster which could 
be used for low-level or glide bombing attacks. 

Penetrating Power. A number of hits were 
obtained on the industrial target building at 
Eglin Field, Florida. One bomb penetrated the 
6-in. reinforced concrete roof slab and an 8-in. 
reinforced concrete floor, and then ejected its 
gel and disintegrated from premature detona¬ 
tion of its high-explosive charge. A second 
bomb showed similar penetration of roof and 
floor, but failed to function. Upon hitting the 
next lower floor the nose assembly parted from 
the case. Two bombs which hit light roof con¬ 
struction penetrated cleanly and also went 
through a plain 6-in. concrete floor, coming to 
rest about 1 ft below the floor. The incendiary 
gel was ejected; one HE charge detonated pre¬ 
maturely and the other after the intended 
delay. No instance of rupture of the bomb case 
upon impact was noted, and there were no 
failures of the nose and case to hold together 
until after the roof had been penetrated by 
the bomb. 


When impacting on sand or clay, in drops 
from high altitude, the E9 bomb penetrated 12 
ft or more into the ground. Ejection occurred 
after the bomb had gone some distance below 
the surface, and no incendiary results were to 
be expected. 

Fire Starting Efficiency. The end of World 
War II came before tests could be run to evalu¬ 
ate the fire starting efficiency of the E9 bomb 
when actually dropped onto combustible tar¬ 
gets. The test mortar, used to determine the 
optimum fuel for the bomb, simulated the 
original design in which a delay element per¬ 
mitted the bomb to come to rest before ejection 
occurred. The final design omitted the delay, 
so that ejection occurred in a few hundredths 
of a second after the first impact. But this per¬ 
mitted a bomb that hit on the ground to pene¬ 
trate to the point where no gel was discharged 
above the surface; hence, only direct hits on 
structures would be significant. From the 
meager data available it appeared that ejection 
of gel would occur while the bomb was still in 
flight after penetrating roofs and floors equiva¬ 
lent to the 6-in. roof and 8-in. floor actually 
penetrated in two instances. Or, after penetrat¬ 
ing a light roof in a one-story building the 
bomb would go through a 6-in. floor and eject 
its gel upward from its final position just below 
the floor. 

Neither of these modes of functioning was 
favorable to the starting of a fire, as compared 
to the horizontal ejection of gel that was 
originally planned. However, with approxi¬ 
mately 10 lb of incendiary gel being ejected, 
there would be a good chance that several gobs 
























40 


LXCEXDIARY B03IBS AND CLUSTERS 


of substantial size would be thrown against 
combustible material. Moreover, the chance of 
starting several simultaneous fires which 
would be mutually supporting increased with 
the amount of fuel in the bomb. Hence it may 
be said that the E9 bomb would probably prove 
to be an effective fire starter, and would be 
especially valuable for the attack on selected 
targets where precision bombing and the ability 
to penetrate a substantial roof were necessary. 

It appears unlikely that a bomb of this type 
could be constructed which would regularly 
hold together until it came to rest before ejec¬ 
tion. The E9 showed no sign of failure in pene¬ 
trating the roof and floor slab, but in one in¬ 
stance the nose separated from the casing when 
the next floor was encountered. In slowing 
down as it passes through roofs and floors, the 
bomb is certain to turn so that the next impact 
will not be taken on the nose and in line with 
the central axis of the bomb. When that occurs, 
breakup is to be expected. Hence it appears 
necessary to have the bomb function instan¬ 
taneously, and a more rapid ejection than was 
achieved in the E9 would have some advantages. 
Hits on the ground might not be a total loss, 
and hits on one-story factories would result in 
gel being ejected between roof and floor with¬ 
out having to depend on there being a heavy 
concrete floor to stop the bomb where its gel 
would still be ejected inside the structure. 


Table 7. Fragmentation of E9 incendiary bomb. 


Description 

Number 

Weight 

Unfragmented portion of case 

Large fragments. ^ lb and over 
Medium fragments, 1-8 oz 

Small fragments, 0.2-1 oz 

Small fragments, 0.2 oz and smaller 

1 

8 

40 

100 

1,000 approx. 

6 lb,15 oz 
5 lb,12 oz 
5 lb, 15 oz 
2 lb, 2 oz 
2 lb, 10 oz 

Total 

1,150 approx. 

22 lb, 12 oz 

Original weight of metal, 21 lb, 3 oz 
Recovery, 91.1% 



Fragmentation. A test made in a fragmenta¬ 
tion chamber at Edgewood Arsenal gave results 
shown in Table 7. The detonation of the E9 
anti-personnel element makes a very impressive 
noise, and in field trials fragments were found 
1/4 mile from the point of explosion. 


Final Status 

When World War H ended, some minor prob¬ 
lems remained to be solved in perfecting the 
E9 bomb and the E53 cluster. In summarizing 
this development, the following conclusions ap¬ 
pear to be justified. 

1. The E9 is a medium-sized incendiary 
bomb which has excellent ballistic characteris¬ 
tics. It can be aimed with current bombsights 
and has a small trail angle compared to most 
of the other incendiary bombs. 

2. The penetrating power on reinforced con¬ 
crete exceeds the stated requirements for this 
bomb, and the performance after penetration 
appears satisfactory. 

3. The quantity of incendiary fuel per cluster 
is greater than for any other comparable cluster 
of bombs using gelled fuel. 

4. A lethal anti-personnel charge was suc¬ 
cessfully incorporated, but some further work 
is required to prevent premature functioning 
of the HE. 

5. Some changes in details of the bomb-fuze 
mechanism are needed to prevent malfunction¬ 
ing on impact. 

6. The E26 cluster adapter is capable of re¬ 
leasing the bombs with a minimum of tumbling. 
It utilizes all the space available in a 500-lb 
bomb station, and its components fall rapidly 
enough to clear lower flying planes in a forma¬ 
tion. 

7. The E53 cluster is suitable for high-level, 
low-level, and glide bombing. 

8. The E9 bomb and E53 cluster are ade¬ 
quately safe to handle, transport, and store. 


1" E3, 25-LB OIL INCENDIARY BOMB 

Development of this bomb was initiated in 
April 1942 by Harvard University under Con¬ 
tract OEMsr-179. The objective was to develop 
a medium-sized incendiary bomb which would 
be an improvement on the AN-M46, 30-lb bomb, 
from the point of view of flight stability and 
functioning, and on the AN-M47, 70-lb bomb, 
from the point of view of clustering and loading 
efficiency. The E3 bomb could be considered 
either as a small version of the AN-M47 bomb. 








E22, 500-LB OIL INCENDIARY BOMB 


41 


or as an improved version of the AN-M46 bomb. 
Some impetus also came from the British 30-lb 
petrol gel bomb, which was of the same size 
class. The E3 bomb can be considered as a pre¬ 
cursor of the E9, 40-lb oil incendiary bomb (see 
Section 1.6). 

The E3 bomb was of the 25-lb class and of 
the bursting type. It was intended to be clus¬ 
tered 14 in a 500-lb size quick-opening cluster. 
The bomb consisted of a hexagonal sheet steel 
case with an ogival nose and a conical tail 
section fitted with a fixed hexagonal steel fin. 
A central burster was of the WP-HE type as 
in the AN-M47 bomb. The filling was 13.5 per 
cent Napalm gasoline gel. The nose was fitted 
with an AN-MllO arming vane type fuze. The 
overall dimensions were 4% in. across the hex¬ 
agonal flats by 26% in. long. The filled weight 
was 23.5 lb, of which 11 lb was gasoline gel. 
The proposed 500-lb size cluster would have 
been approximately 141/4x58 in. and would 
have weighed approximately 375 lb. 

Only two rather crude models of this bomb 
were ever dropped in flight tests. One dropped 
from 2,500 ft at Jefferson Proving Ground 
showed good flight characteristics, and the 
other dropped from 2,500 ft at Edgewood 
Arsenal yawed badly. These results left the 
flight characteristics in doubt, so that this proj¬ 
ect was held in abeyance for some time and was 
later revived in the development of the E9, 
40-lb incendiary bomb. 


18 E20, 500-LB OIL INCENDIARY BOMB 

Development of this bomb was initiated in 
April 1943 by Harvard University under Con¬ 
tract OEMsr-179. The objective was to develop 
a large incendiary bomb with a cast-iron case, 
instead of steel, in order to reduce the force 
necessary to open the case and thereby prevent 
dispersion of fuel in such small particles as 
characterized the performance of the steel-case 
bomb. 

The E20 bomb was very similar to the AN- 
M76 500-lb incendiary bomb, which in turn is 
externally identical with the AN-M64 500-lb 
GP bomb. The principal differences between 
the E20 and AN-M76 bombs are: 


1. The E20 bomb casing is made of cast iron 
instead of steel. 

2. The E20 casing is slightly thicker, with a 
minimum wall thickness of 0.5 in. and a maxi¬ 
mum nose wall thickness of 1.5 in. compared 
with 0.3 in. and 1.25 in., respectively, for the 
AN-M76 casing. 

3. The E20 bomb used a 9/16 in. tetrytol 
burster compared with a % in. burster in the 
AN-M76 bomb. 

4. E20 bombs were filled with Napalm type I, 
methacrylate type I and PTl fillings, although 
part of the purpose of using the cast-iron case 
was to be able to use the Napalm and IM types 
of filling. 

When fired statically the E20 bomb, filled 
with Napalm type 1 and with 9/16-in. tetrytol 
burster, dispersed burning gel over an area 
100 ft X 200 ft. There were 297 fires burning 
after 5 min and 46 fires after 11 min. The 
casing broke into many small pieces. 

When dropped on buildings from 4,000-5,000 
ft, the bomb functioned satisfactorily on strik¬ 
ing light roofs. One bomb penetrated a light¬ 
weight, concrete tile roof and also a 3-in. con¬ 
crete slab floor, depositing gel on the first floor 
over an area 120 ft x 180 ft, with 235 fires burn¬ 
ing after 5 min. However, when striking a 7-in. 
reinforced-concrete slab the bomb broke up 
so badly that satisfactory penetration and 
functioning on heavy-roofed buildings seemed 
doubtful. The E20 bomb is therefore not a sub¬ 
stitute for the AN-M76 in this respect. 

When dropped 10 ft and 20 ft onto concrete, 
the bomb broke into 6 to 18 pieces. This fact 
ruled out the bomb from a safety point of view, 
and further development was discontinued. 


E22, 500-LB OIL INCENDIARY BOMB 

Development of the bomb was initiated in 
April 1945 by the Factory Mutual Research 
Corp. under Contract OEMsr-257. The objective 
was to develop a large incendiary bomb of the 
tail-ejection type, using cellucotton as the body¬ 
ing agent for gasoline fuel instead of gelling 
agents such as Napalm. 

The E22 bomb was an attempt to develop a 
large tail-ejection type incendiary bomb to meet 



42 


INCENDIARY BOMBS AND CLUSTERS 


the requirement for a 500-lb size incendiary 
bomb. This bomb used the casing of the AN- 
M64 500-lb GP bomb, modified somewhat, and 
therefore was externally identical with the AN- 
M76 500-lb incendiary bomb. 

The principal components of the E22 bomb 
were the following. 

1. The AN-M64 bomb case scored to a depth 
of 9/32 in. clear around at the base of the tail 
cone (% thickness of the casing). 

2. A nose burster consisting of a steel wall 
1% in. in diameter by 18% in. long extending 
inside the bomb case and filled with 250 g of 70 
per cent A4 black powder and 30 per cent coarse 
magnesium flakes. 

3. A cylindrical tail canister containing 5 lb 
of white phosphorus. 

4. A main filling consisting of 92 cellucotton 
rolls, 4 in. X 4 in., covered with cheesecloth and 
17 gal, or 110 lb, of gasoline. Gel type fillings 
could also be used. 

5. An AN-M103 nose fuze, with the charge 
reduced from 50 g to 5 g of tetryl, set for in¬ 
stantaneous firing. 

6. An AN-MlOl A2 tail fuze and M115 
burster containing 100 g of tetryl, set for 0.025- 
sec time delay. 

The gross weight of the bomb was about 375 
lb, and the external dimensions and appearance 
were identical with the AN-M64 and AN-M76 
bombs. 

On functioning, the burster charge blew off 
the scored tail section and ejected the gasoline- 
soaked cellucotton rolls. The spectacular action 
earned this bomb the name volcano bomb. In 
static tests about 92 per cent of the cellucotton 
units were ejected whole with 85 per cent igni¬ 
tion. At the end of 10 min 57 fires were still 
burning. There was a large flash burn of excess 
gasoline at the time of ejection, but this was 
estimated to consume less than 10 per cent of 
the gasoline in the bomb. The white phosphorus 
canister in the tail was burst by the M115 
burster and produced an instantaneous white 
smoke. 

Dropping tests were few and inconclusive. A 
total of 10 bombs were dropped from 5,000 ft 
altitude, of which 3 hit a building and 7 hit 
onto ground. The bombs which hit buildings 
seemed to fragment the case rather than simply 


eject the contents, and there was an unusually 
large amount of flash burn. Also the cellu¬ 
cotton rolls were shredded and shattered more 
than in the static tests. However, in one case 
there were 56 fires burning at the end of 5 min. 
The general conclusion was that the bombs did 
not function the same or as promisingly in the 
dropping tests as in the static tests. One bomb 
penetrated two floors of 7 in. and 8 in. of con¬ 
crete respectively, showing its penetrating 
power to be comparable to the AN-M64 or 
AN-M76 bombs. The bombs striking onto 
ground did not add any pertinent data. 

Although the results were not conclusive, the 
development was discontinued at this point in 
view of the AN-M76 filling the limited require¬ 
ments for this class of incendiary bombs. 


1PLASTIC INCENDIARY BOMB 

Development of this bomb was initiated in 
December 1941 by the Monsanto Chemical Co. 
under Contract OEMsr-198. The objective was 
to develop a small incendiary bomb utilizing 
cellulose nitrate plastic as an incendiary ma¬ 
terial. 

Two principal types of bombs were developed 
under this project. 

1. Bombs in which the cellulose nitrate plas¬ 
tic served as a combustible casing for a 
therm-8 filling, i.e., the plastic was intended 
to be an improved substitute for the steel casing 
in the AN-M54 type of incendiary bomb. 

2. Bombs in which the cellulose nitrate plas¬ 
tic was the primary incendiary material with 
only enough therm-8 filling to assist the burn¬ 
ing of the plastic. 

The various bombs developed under this proj¬ 
ect were hexagonal in shape, 1% in. across the 
flats by 10 in. long, or roughly half of the length 
of the AN-M50 and AN-M54 standard bombs. 

Many variants of bombs of the first type 
were tried, and the most important and final 
model had the components described below. 

Plastic casing, hexagonal, 1% in. across fiats 
by 10 in. long, with inside bore of 1% iii- or 
IV 2 in., giving a minimum wall thickness of 
% in. or % in., respectively. 

Steel nose plug, with hexagonal section % in. 



PLASTIC INCENDIARY BOMB 


43 


thick and a %-in. long section extending inside 
the plastic casing. 

Plastic tail plug, made of Resinox plastic, 
ll^ in. in diameter, in. long, bored in¬ 
ternally to take the firing pin, spring, and 
primer holder from the AN-M54 bomb. 

Filling of 5 pellets of therm-8, each 1 in. 
thick, and 1 first-fire pellet. 

Cloth tape tail streamer, 1 in. wide, 30 in. 
long. Various other bombs with tails and bombs 
without tails were also tried. 

The gross weight of a bomb of this descrip¬ 
tion was 2l^ lb; the burning time was 21/0 min* 

Drop tests from 1,000 ft onto concrete re¬ 
sulted in breaking and malfunctioning of these 
bombs, although the flight stability was good. 
Somewhat better performance on drop tests 
was obtained by wire reinforcing in the plastic 
and by use of layer-cloth, tail streamers, and 
parachutes, but the results were still discourag¬ 
ing. These results caused abandonment of this 
type of bomb. 


Bombs of the second type were similar to 
those of the first type, except that the bore 
of the plastic casing was reduced to 1/2 
making the bomb primarily a plastic bomb with 
just enough therm-8 to assist the burning of 
the cellulose nitrate. These bombs weighed only 
1.6 lb compared to 2.25 lb for the first type, 
so that it was felt the bomb was sufficiently 
nose heavy with the steel nose plug that the 
cloth tail could be omitted. Drop tests from 
1,000 ft onto concrete showed adequate strength 
and apparently good flight stability. However, 
drop tests from 5,000 ft and 10,000 ft showed 
very poor flight stability, many bombs tumbling 
badly. 

In view of these test results development of 
this bomb was discontinued in the summer of 
1942. Furthermore, comparative burning tests 
showed that the fire starting capacity of this 
bomb was quite low, reflecting the relatively 
low heat of combustion of cellulose nitrate 
(7,200 Btu per lb). 




Chapter 2 

MISCELLANEOUS INCENDIARY ITEMS 


21 INTRODUCTION 

T his chapter describes miscellaneous de¬ 
velopments in the incendiary field, includ¬ 
ing a new type of burster for large incendiary 
bombs which was utilized in the AN-M47 and 
AN-M76 bombs, several small incendiaries for 
sabotage and other miscellaneous purposes, an 
all-ways fuze for M69 type bombs, incendiary 
leaves, and certain modifications of some 
standard incendiary bombs. Most of these de¬ 
velopments could be described as minor, except 
the new type burster for large incendiary 
bombs. 


2 2 BURSTER-IGNITER FOR M47 TYPE BOMBS 
Introduction 

All the incendiary bombs used in World War 
II were exploded by either base-ejection or 
central charges of black powder. Chemical 
bombs, on the other hand, scattered their con¬ 
tents by means of a central burster, usually of 
tetryl. The phosphorus bombs or shells con¬ 
structed in this manner were poor incendiaries 
at best, and the bursting charge was so great 
that most of the contents were broken into very 
small particles. With the development of gaso¬ 
line fuels thickened by rubber or Napalm, a new 
and comparatively difficult problem of ignition 
and distribution arose. It was necessary to dis¬ 
tribute the burning gel in gobs sufficiently large 
to start fires under average conditions. Very 
large lumps may burn for a long time, but they 
represent an inefficient distribution, while very 
fine pieces of gel are too short-lived to be effec¬ 
tive. 

It was found that the M47 series of 100-lb 
chemical bombs, which make efficient containers 
for incendiary material, burst unevenly under 
slowly increasing pressure such as produced by 
a black powder burst. Usually there was one 
weak spot at a seam or near the tail that would 
rupture sufficiently to release the pressure and 


eject only a portion of the fuel, while the re¬ 
mainder burned either in the bomb or in the 
crater below. This was verified by high-speed 
motion pictures (800-1200 frames a sec) with 
the M47 100-lb bomb having a 0.032-in. wall, 
and the same effect was later observed, to a 
lesser degree, with the M47A1 bomb having a 
0.050-in. wall. Bombs loaded with chemical 
agents did not exhibit this fault, for the liquid 
transmitted the pressure practically undi¬ 
minished, but the jellied fuels absorbed much 
of the energy, causing a slower transmission 
of the bursting energy to the case. 


Description 

It was observed that light-wall gallon cans 
used to test experimental batches of thickened 
fuel were effectively scattered by one or more 
detonators. From this observation it was rea¬ 
soned that a high-explosive central core of 
primacord or TNT-tetryl should act similarly, 
and this was found to be the case. A means hav¬ 
ing been found for distributing the gelled fuel 
evenly and in regulated size, a large number of 
igniters were then examined in order to effect 
ignition of the gel. Among those tried were 
powdered and grained magnesium, sodium, 
potassium, sodium-potassium alloy, zinc di¬ 
methyl, silicon ethyl, phosphorus, and pyro¬ 
phoric metals. Larger scale tests were then 
made on zinc dimethyl and phosphorus con¬ 
fined in an annular tube surrounding the cen¬ 
tral explosive core. Phosphorus was found to be 
the better of the two, and from practical con¬ 
siderations of manufacture and loading it was 
selected as the igniter to be used in conjunction 
with the high-explosive burster.^’ ^ 

The experimental model is shown in Figure 
1. In this unit the central explosive core 31 con¬ 
sists of TNT pellets, contained in a bakelite 
tube with one or more booster pellets of the 
more sensitive tetryl at either end. Light brass 
or aluminum caps retain the pellets in the tube 
and permit firing the tube at either end. The 


44 


BURSTER-IGNITER FOR M47 TYPE BOMBS 


45 


burster is held against the fuze by the coil 
spring 32 which is an integral part of the outer 
housing. Considerable leeway is permitted in 
the gap between the fuze and the end of the 
burster, and reliable firing is obtainable with 
gaps of from Vs to % in. in length. Two pounds 
of phosphorus is contained in the annular space 
between the inner burster well and the outer 
tube. A seal made by the lead washer 26, to¬ 
gether with a luting of pipe dope (hydraulic 
cement ground with linseed oil), retains the 
phosphorus. 


never produced, but after some delay the Chem¬ 
ical Warfare Service modified it somewhat and 
it was standardized and produced as the AN- 
M13 burster and AN-M9 igniter for use in 
AN-M47 series bombs.'*- ** These items were 
produced and supplied separately so that each 
was made a sealed unit, with the result that the 
total wall thickness required to be ruptured was 
increased so much that the production models 
never equalled the experimental models in per¬ 
formance. The AN-M13 burster is a plastic or 
aluminum tube, 0.45 in. diameter, 36 in. long, 


22 34 18 16 14 13 



Figure 1. WP-HE burster-igniter in place in AN-M47 incendiary bomb and detailed cross section. 


The phosphorus was loaded by either the 
wet method (under water) or the dry method 
(under carbon dioxide) The latter method was 
preferred and largely used in production, be¬ 
cause of the lessened chance for corrosion. The 
phosphorus was loaded and sealed into the 
burster well in the factory, and the sealed tube 
of explosive was inserted into the central well 
in the field at the time of arming. 

The burster-igniter as described above was 


filled with TNT pellets containing tetryl pellets 
at each end. The AN-M9 igniter is a steel tube, 
38.5 in. long, filled with 1.6 lb of white phos¬ 
phorus (WP), and containing a steel well, 
0.454-in. inside diameter, to receive the AN- 
M13 burster. This combination was used exten¬ 
sively in AN-M47 bombs in bombing Germany 
and Japan. The AN-M12 black powder-mag¬ 
nesium powder burster was also used in this 
bomb. Tests at Eglin Field failed to show con- 







































































46 


MISCELLANEOUS INCENDIARY ITEMS 


elusive superiority for either of these competi¬ 
tive bursters. 

This same principle was adopted for use in 
the AN-M76, 500-lb incendiary bomb. This 
bomb was a standard 500-lb^ bomb case filled 
with 180 lb of PT incendiary gel. The M14 
burster and M5 igniter for the AN-M76 bomb 
were of the same type as the AN-M13-M9 com¬ 
bination used in the AN-M47 bomb. The M14 
burster contained one lb of tetrytol, and the 
M5 igniter contained 9 lb of white phosphorus. 
This combination worked quite successfully in 
this bomb. The AN-M76 bomb was used to a 
limited extent in bombing Germany and Japan. 

Another application of this burster-igniter 
principle was used by the Chemical Warfare 
Service in the burster-igniter for the jettison- 
able belly tanks, or fire bombs, filled with 
Napalm gasoline gel, which were used so effec¬ 
tively in Europe and the Pacific. 

^ ^ Performance Data 

This type of burster is always instantaneous 
firing. In testing this type of burster a sharp 
distinction must be made among three methods 
of testing: 

1. Firing of statically placed bombs, in which 
the fuel is thrown outwards and upwards in a 
fairly circular pattern with the bomb at the 



Figure 2. Static burst of AN-M47 incendiary 
bomb using WP-HE burster-igniter. 


center (Figure 2). A typical burst of this type 
would cover an area about 150 ft across and 
would yield about 50 gobs of gel which would 
still be burning after 10 min. 


2. Bombs dropped from airplanes onto earth, 
in which the bomb makes a crater and most 
of the fuel is thrown forward and upwards in 
an elliptical pattern with the bomb at one end. 
The area covered was about 50x100 ft, al¬ 
though this varied with the angle and speed of 
impact. 

3. Bombs dropped from airplanes onto build¬ 
ings, in which the bomb bursts 8 to 15 ft be¬ 
low the roof and the fuel is thrown downwards 
and outwards in a conical pattern onto the floor 
below. 

Figure 2 shows a burst of type (1). Bombs 
were frequently tested by method ( 2 ) in the 
early days of World War II, and some limited 
conclusions could be drawn. Tests by methods 
(1) and (2) in 1942 indicated a marked su¬ 
periority of the WP-HE burster over the black 
powder-magnesium powder burster,*^’ •*’ and 
this led to the decision to use the former. How¬ 
ever, only tests by method (3) are really sig¬ 
nificant in determining the effectiveness of a 
bomb. Tests by this method at Eglin Field in 
194411 , 12,13 failed to show any marked superior¬ 
ity of the AN-M13-M9 burster-igniter combina¬ 
tion over the AN-M12 black powder-magnesium 
powder burster. It is possible that a better ad¬ 
justment of HE charge and wall thickness of 
material in the AN-M13-M9 combination might 
have given the superior results shown by the ex¬ 
perimental model. 


2 3 SABOTAGE INCENDIARIES AND 
FIRE STARTERS 

Introduction 

Small pocket-size incendiaries of this type are 
used as sabotage incendiaries, usually placed by 
hand, and for starting campfires in the field, or 
for heating and cooking in emergencies. The 
following NDRC contractors developed incendi¬ 
aries of this type: 

Harvard University, Contract OEMsr-179; 
Factory Mutual Research Corp., Contract 
OEMsr-257; and University of Chicago, Con¬ 
tract OEMsr-113. The first two contractors later 
worked directly with the Office of Strategic 
Services in this line of development. 






SABOTAGE INCENDIARIES AND FIRE STARTERS 


47 


All incendiaries of this type consist essen¬ 
tially of a combustible case, filled with some in¬ 
cendiary material, and fitted with some sort of 
igniter. 


" "" Ml, Fire Starter 

This unit, developed by Harvard University, 
consists of a cylindrical celluloid case, 3xli/>-in, 
diameter, filled with 33 g of Napalm gasoline 
gel, and fitted with a match-head and scratcher 



Figure 3. Ml fire starter (Harvard Candle), as¬ 
sembly and construction. 


igniter (Figure 3 ) i'-. le. is. lo gross 

weight of the unit is 77 g, its heat output is 
about 1,700 Btu, and it burns for 7 to 9 min. 
The match-head composition is 50 per cent po¬ 
tassium chlorate, 30 per cent antimony sulfide, 
20 per cent dextrin, and water to give a stiff 
paste. The scratcher composition is 50 per cent 
red phosphorus, 30 per cent 50-80 mesh sand, 
20 per cent dextrin, and water to give a stiff 
paste. The complete unit is waterproofed with 
a coating of vinylite. 

The fire starter is ignited simply by rubbing 


the scratcher on the match-head. This unit was 
tested in a packing box test where two packing 
boxes are placed with 10x25-in. faces, IV 2 in- 
apart. The Ml fire starter started a continuing 
fire in this test setup, while some other small 
incendiaries which weighed more would not do 
so. This test was successful with either dry or 
wet wood. Other simple wood-burning tests 
were used in which the Ml fire starter showed 
up to advantage compared to other incendiaries 
of similar weight. 

This incendiary, originally called the Har¬ 
vard Candle, was standardized as the Ml fire 
starter in 1942 and produced in some quantities. 
There is no record of its use in the field. 


2.3.3 jj2^ Vest-Pocket Sabotage Incendiary 

This device, developed by Harvard Univer¬ 
sity, is made to resemble a plastic cigarette 
case or notebook (Figure 4).-*^ It consists of a 
black celluloid case 5U(;x2%x% in., filled 
with 133 g of 8 per cent Napalm gasoline gel 
and fitted with a time-delay ignition mechan¬ 
ism. The gross weight is 189 g, the heat output 
is about 5,500 Btu, and the burning time is 
about 15 min. 

The time-delay igniter on this unit had to be 
safe, reliable, silent, and waterproof. It con¬ 
sisted of a standard OSS time-delay pencil actu¬ 
ating a spring-loaded firing pin, which pierced 
a thin, 0.005-in., celluloid cylinder and fired an 
ordinary strike-anywhere match-head. The OSS 
time-delay pencil consisted of a metal wire 
holding a spring-loaded firing pin and a glass 
tube of corrosive liquid contained in a thin 
metal tube which could be pinched to break the 
glass tube and initiate the mechanism. The fire 
of the match-head was passed on to the main 
gasoline gel filling by a potassium chlorate 
booster charge. 

The high Btu output of the H2 incendiary 
gives a high fire-starting power. On packing- 
case tests, piles of faggots and logs, a wooden 
attic, and stacks of packing cases, the H2 was 
demonstrated to be a potent fire starter. The H2 
incendiary was produced in large quantities by 
the Office of Strategic Services and used abroad 
in sabotage operations. 



48 


MISCELLANEOUS INCENDIARY ITEMS 



CEMENTED CASE CONTAINING 
10.6 g. NAPALM POWDER 









I; 


VARSOL (I22.4g.) INJECTED, 
GELATION COMPLETE 



H-2, COMPLETE WITH PENCIL 
{TOTAL WEIGHT, 189 OZ.) 


Figure 4. H2 vest-pocket sabotage incendiary, as¬ 
sembly, and construction. 


2.3.4 pjyj gaijojage Incendiary 

This unit, developed by the Factory Mutual 
Research Corp., consists of a celluloid case, 
5x2%x% in., filled with cotton waste and paraf¬ 
fin wax in which are embedded two cores, 5x1/2 
in., made of 45 per cent sodium nitrate, 35 per 
cent aluminum powder, 15 per cent SAE 40 
motor oil, 5 per cent sulfur.^®- The gross 
weight of the unit is 175 g. The units were ig¬ 
nited by means of a temporary first-fire charge, 
but a time-delay igniter could be fitted to it for 
actual use. 

These units were tested by burning them 
between two packing case ends, 24x45 in., 
placed 3 in. apart, as representative of a sabo¬ 
tage location in a warehouse or supply dump 
(see Section 3.2 for further description and 
photographs of this test arrangement). The 
FM incendiary set fire to such a setup when 
dry, after being soaked in water, and after 
being soaked in water and covered with snow, 
although, of course, the speed of starting the 
fire varied with the conditions. 

The FM incendiary was competitive with the 
H2 vest-pocket incendiary. The FM unit had 
the advantage that the filling was stable over a 
wide range of temperatures, it was not subject 
to leakage or evaporation, and it would stand 
very rough handling without malfunctioning. 
Its fire starting efficiency was comparable to the 
H2 unit. However, the H2 incendiary was se¬ 
lected for production and use in this class of 
incendiary. 


These incendiaries, developed by the Univer¬ 
sity of Chicago, were made in a variety of sizes 
and types of cases. All were filled with a mix¬ 
ture of polymerized divinylacetylene (SDO, syn¬ 
thetic drying oil, a du Pont product), sodium ni¬ 
trate, and heavy petroleum oil (Figure 5) 

The composition of the mixture was 30 per cent 
SDO, 60 per cent sodium nitrate, and 10 per 
cent oil. This project was originally started in 
the belief that SDO was an incendiary material 
of superior merit, because it ignited readily and 
had accidentally caused some bad fires in 


Chicago Hand Incendiaries 







E16, ALL-WAYS FUZE FOR AN-M69 TYPE BOMBS 


49 



Figure 5. Chicago hand incendiaries, external 
views and method of igniting. 


laboratories. However, further investigation 
showed that the heat output of SDO was the 
same as that of other hydrocarbon materials, 
and that it really had no superior fire starting 
ability. This mixture was placed in tubes made 
of paper, cellulose acetate, or magnesium. The 
principal sizes used were approximately %x7i/2 
in., %x4% in., ll^x7V2 in., and ll/i,x3 in. The 
units were fitted with a match-head and 
scratcher similar to that of the Ml fire starter. 

The SDO-sodium nitrate mixture burned with 
a blowtorch flame which would melt and ignite 
a magnesium casing. The flame was impressive, 
but in comparative tests in packing cases these 
units were not as effective in starting fires as 
Ml fire starters which weighed less. Develop¬ 
ment was discontinued in 1942. 


2-1 E16, ALL-WAYS FUZE FOR 

AN-M69 TYPE BOMBS 

At one time the stability of AN-M69 bombs 
when dropped in aimable clusters was in doubt. 
Therefore development of an all-ways fuze for 
this bomb was initiated in the spring of 1944 



Figure 6. E16 all-ways fuze for AN-M69 type 
bombs. 


by Arthur D. Little, Inc., under Contract 
OEMsr-242. This fuze was to be able to fire at 
all angles of impact with a sensitivity com¬ 
parable with that of the Ml fuze, was to be 
waterproof and have a reliable safety device 



















































































































50 


MISCELLANEOUS INCENDIARY ITEMS 


which would be operative up to the moment of 
stacking for clustering. 

Figure 6 shows the design of the E16 fuze.-^ 
The firing-pin plunger A carries the two balls B 
which, when held apart by the safety pin C, pre¬ 
vent the firing-pin plunger from entering the 
primer holder B. Parts A and D are made of 
either brass or aluminum. The primer used is 
the M29 and is located in the cavity E. The 
firing pin F is of the type that has a rounded 
end with a radius of curvature of 0.046 in. The 
firing pin is normally kept away from the firing 
cap by the spring G. The assembly with the 
firing-pin plunger A is forced down onto the 
primer when the bomb lands because of inertia 
in either longitudinal direction, or by a squeez¬ 
ing action if it lands sidewise due to the curved 
surface H. 

The safety and waterproofing features are 
contained in the top plug assembly. The safety- 
pin cap I is assembled to the safety pin C so 
that the joint is waterproof. This assembly is 
forced toward the top by the spring J so that 
the safety pin C is disengaged from the balls, 
unless a force is exerted on the top plunger. 
The top plunger K is separated from the safety 
cap by the spring L. The spring L has only a 
small normal extension with the result that the 
parts lie much as shown in the lower view on 
the subassembly drawing of the top plug when 
no force is applied to the top plunger. When the 
top plunger is pushed in, the safety pin C 
enters to spread the balls B apart and the 
safety-pin cap flange comes down on the Neo¬ 
prene gasket M making a watertight joint. The 
spring L is necessary only to provide some 
tolerance for its position when held in place by 
the other bombs. 

The tube 0 has a groove P against which the 
bottom plug Q seats. The top plug assembly is 
then held tightly against the bottom Q by 
crimping in the top of the tube, as indicated at 
R. The chamber S is provided to take the 
booster charge. Provision was made for a delay 
train to be put in the hole T. If no delay is 
wanted, this hole can be left empty. This fuze 
is of the same external dimensions as the pres¬ 
ent Ml fuze in the AN-M69 bomb, and can be 
substituted for it without any changes in the 
bomb. 


Tests were made by dropping from small 
heights onto concrete at various angles. The 
limits found were 2 to 6 ft, none firing at less 
than 2 ft and all firing at 6 ft, with a large per¬ 
centage firing at 5 ft. The sensitivity can be 
adjusted by varying the weights of parts A and 
D, the tension of spring G, and the clearance 
between the top of the primer and the end of 
the firing pin F. The shape of the contour H is 
not particularly important. 

In the spring of 1945, 500 experimental 
models of the E16 fuze were turned over to the 
Chemical Warfare Service for final development 
and production if needed. However, the sta¬ 
bility of the AN-M69 bomb in aimable clusters 
appeared to be satisfactory so that the E16 
fuze would probably not have been needed. 

2 5 Ml INCENDIARY LEAF 

Development of this item was initiated in 
September 1940 by Brown University under 
Contract OEMsr-57. The objective was to de¬ 
velop an impact-sensitive ignition coating for 
incendiaries, especially celluloid incendiary 
leaves. The British had used incendiary leaves 
early in World War II using white phosphorus 
as a means of spontaneous ignition, and impact- 
sensitive ignition coating appeared to have pos¬ 
sible merit. 

The principal incendiaries for which this 
coating is intended are celluloid disks approxi¬ 
mately 7.7-in. diameter by i/4 in. thick. The 
result is an incendiary leaf which fires on im- 
pact.25. -c. 27 steps in producing the impact- 
sensitive coating are as follows. 

1. The disks are immersed in a solution com¬ 
posed of 5.0 per cent polyvinyl alcohol (du Pont 
RH-428), 47.5 per cent methyl alcohol, 45.5 per 
cent water, and then dried in air. The purpose 
of this coating is to protect the celluloid against 
the action of the storage liquid, which is prin¬ 
cipally carbon tetrachloride. 

2. About V-y in. of the periphery of the disks 
is coated with red phosphorus by rotating the 
disks at a predetermined depth of immersion 
in either of tw^o suspensions. Suspension A has 
the composition 17.4 per cent red phosphorus, 
1.5 per cent calcium carbonate, 4.1 per cent 
celluloid, 77.0 per cent nitromethane. Suspen- 




MODIFIED AN-M52 BOMB FOR LIGHT STRUCTURES 


51 


sion B has the composition 29.3 per cent red 
phosphorus, 2.4 per cent calcium carbonate, 
6.8 per cent celluloid, 61.5 per cent acetone. This 
coating is then dried in air. 

3. The phosphorus coating is then covered by 
a sensitizing coating by rotating through a 
solution composed of 17.6 per cent sodium per¬ 
chlorate, 4.5 per cent pyroxylin, 23.4 per cent 
ethyl acetate, 54.5 per cent acetone. This coat¬ 
ing is dried in air with a relative humidity of 
at least 60 per cent to prevent spontaneous 
ignition. 

4. Final dehydration and drying is then ac¬ 
complished by suspending the disks in boiling 
carbon tetrachloride, or its vapors, until they 
are sufficiently dried to become sensitive. 

5. The sensitized disks are packed in a cylin¬ 
drical metal container in which they are im¬ 
mersed in a storage solution composed of 80 to 
85 per cent carbon tetrachloride and 15 to 20 
per cent heptane. 

This coating remained sensitive on storage 
for 155 days at 60 centigrade and for 230 days 
at room temperature. Surveillance was discon¬ 
tinued at these times so that the stability for 
longer times is not known. Coatings employing 
sodium chlorate or potassium chlorate did not 
remain sensitive for periods of more than a 
few weeks, and they were discarded for this 
reason. 

These incendiary leaves were carried in air¬ 
planes in cylindrical metal bomb cases provided 
with a time fuze for opening and discharge of 
the leaves at a predetermined altitude. The 
disks were blown out of the tail end of the 
bomb case by an explosive charge in the nose, 
and after drying out in flight, the leaves would 
ignite on impact on the ground or a building. 
However, on flight tests it was found that many 
of the leaves were ignited in the air by the force 
of the ejection, while many would still not ig¬ 
nite on impact on the ground. This showed that 
the limits of allowable sensitivity were quite 
narrow and great uniformity of the sensitive 
coating would be necessary for satisfactory 
performance. The development was discontin¬ 
ued at this point, although some experiments 
indicated that several means might be used for 
preventing the ignition of leaves on discharge 
from the bomb case. 


It should be mentioned that the M2 incen¬ 
diary leaf, developed by Chemical Warfare 
Service in parallel with the Ml leaf, consisting 
of a celluloid disk with an insert of white phos¬ 
phorus, similar to the original British leaves, 
looked considerably more promising than the 
Ml leaf. Development of both these items was 
discontinued because the requirement for this 
type of incendiary was dropped. 


26 MODIFIED AN-M52 BOMB EOR 
LIGHT STRUCTURES 

Ever since the tests at Dagway Proving 
Ground in June and July 1943, it had been 
apparent that the AN-M52, 2-lb magnesium 
bomb had definite possibilities for area incen¬ 
diary attacks in Japanese cities (see Section 
3.4). However, the AN-M52 had excessive pene¬ 
trating power for one-story Japanese houses at 
its normal striking velocity of about 325 ft per 
sec, and the bomb was on the verge of being 
unstable because the center of gravity was 
about 51/2 in- back from the nose. Therefore, 
the problem of correcting both these features 
was assigned to Harvard University under 
Contract OEMsr-179 and the Factory Mutual 
Research Corporation under Contract OEMsr- 
257. 

The first step was to build some Japanese 
structures and determine the proper striking 
velocity of the AN-M52 bomb by shooting 
bombs down onto the structures at various 
velocities from an overhead mortar. Variables 
studied were one-story and two-story struc¬ 
tures, tile and sheet-metal roofs, presence and 
absence of tatami mats on floors. It was found 
that the tatami mats offered the greatest re¬ 
sistance to passage of the bomb. On the basis 
of these tests it was concluded that the effective 
striking velocity of the AN-M52 could be any¬ 
where between 200 and 300 ft per sec, with 
225 ft per sec selected as the optimum value if 
the distribution of one-story and two-story 
houses was assumed to be 50-50. 

The striking velocity of the bomb could be 
reduced and its stability improved by the sim¬ 
ple expedient of adding some small cloth 
streamers to the metal tail assembly (Figure 



52 


MISCELLANEOUS INCENDIARY ITEMS 


7).-® Three streamers, % x 36 in., gave the de¬ 
sired striking velocity of 225 ft per sec. Three 
streamers, % x 30 in., gave equivalent results. 
This minor change solved both difficulties of 
the AN-M52 bomb. 



use on light structures. 

In addition to this improvement, the investi¬ 
gators made a further improvement in the in¬ 
cendiary composition of the bomb. The inside 
diameter of the magnesium body was increased 
from 1 to I’Xc, in. and filled with the following 
mixture instead of the standard therm- 8 : 

Flake aluminum 17.1% SAE 40 motor oil 8.3% 

Sodium nitrate 17.0% Sulfur 1.9% 

Barium nitrate 13.5% Thermite 42.2% 


This modified bomb showed some improve¬ 
ment in burning characteristics and fire-start¬ 
ing ability over the standard AN-M52 bomb. 
The oil gave a larger flame, the burning time 
was increased from 65 to 95 sec, the molten 
magnesium did not sputter, and the sulfur di¬ 
oxide gas given off was a valuable fire-fighter 
deterrent. Comparative burning tests in attic 
structures consistently showed a slight advan¬ 
tage in favor of the modified bomb. 


2 ^ MODIFIED FILLING FOR AN-M50 BOMB 

Investigations on various types of thermite 
mixtures at Factory Mutual Research Corpora¬ 
tion under Contract OEMsr-257 had indicated 
that certain mixtures might be superior to ordi¬ 
nary thermite or therm -8 for filling magne¬ 
sium incendiary bombs, especially the AN-M50 
bomb. A mixture which showed great promise 
for this purpose was the following.-*’ 


Aluminum flake 

24% 

Sulfur 

43 

Thermite 

33% 


This filling weighed 210 g, when pressed into 
the AN-M50 bomb body under 26,400 lb per 
sq in., compared to 276 g for the standard 
therm -8 filling. The heat content of the modi¬ 
fied bomb is 16,000 Btu compared to 14,700 Btu 
for the standard AN-M50. This filling melts 
and ignites the magnesium bomb body just as 
well as the standard filling. In addition to a 
higher Btu content, the modified M50 burns 
with a larger flame than the standard bomb, 
the molten magnesium does not tend to sputter 
as much, and the sulfur dioxide generated acts 
as a valuable fire-fighter deterrent. 

Comparative burning tests on attic struc¬ 
tures showed the modified M50 to have a small 
but definite superiority in fire starting over the 
standard AN-M50. Considering all factors, it 
seems probable that use of this filling would 
have materially increased the effectiveness of 
the approximately 250,000,000 AN-M50 and 
British 4-lb bombs dropped in World War II. 
However, these results came too late to permit 
a change in production of the AN-M50 bomb. 






































Chapter 3 

TESTING AND EVALUATION OE INCENDIARIES 


INTRODUCTION 

T he development and application of testing 
methods were important parts of the pro¬ 
gram of all NDRC contractors in the field of 
incendiaries, but the most important contribu¬ 
tions were made by the Standard Oil Develop¬ 
ment Co. under Contracts OEMsr-183 and 354, 
and the Factory Mutual Research Corporation 
under Contract OEMsr-257. In the latter phases 
of World War II also important was the Joint 
CWS-NDRC Incendiary Evaluation Project at 
Edgewood Arsenal, the personnel of which was 
drawn from Factory Mutual Research Corpora¬ 
tion, Massachusetts Institute of Technology, 
under Contract OEMsr-21, Division 11 of 
NDRC, the Office of Field Service of OSRD, 
the Chemical Warfare Service Technical Com¬ 
mand, and the British Ministry of Aircraft 
Production. 

The ultimate objective of testing and evalua¬ 
tion is to ensure that the incendiary will be 
capable of starting fires when it is used in 
actual operations. Final tests should therefore 
approximate as closely as possible the condi¬ 
tions under which the incendiary will have to 
function in actual use. Testing and evaluation 
are necessary at every stage of development, to 
ascertain that the incendiary device and all of 
its components will finally perform in the de¬ 
sired manner. 

The scope of the tests which must be applied 
in the development of incendiary bombs is in¬ 
dicated by the military and technical require¬ 
ments to be met. First and most obvious is the 
requirement that the bomb must exhibit a high 
efficiency in starting fires. It must present no 
undue hazards in manufacture, handling, ship¬ 
ping, and loading into aircraft. It must with¬ 
stand storage for extended periods of exposure 
to the extremes of climate and weather without 
impairing its capacity to function. It must have 
good ballistic properties so as to fall in true 
flight along a predictable path to the target. Its 
mechanical strength must be adequate to sus¬ 
tain the shock and stresses incident to penetrat¬ 


ing roofs and impacting on hard surfaces, with¬ 
out mechanical failure or malfunctioning. The 
fuze must function reliably after penetration 
into the target, and bombs which contain an 
incendiary filling must distribute the filling in 
a manner conducive to effective incendiary ac¬ 
tion. Both the area over which fuel is dispersed 
and the size of the pieces of fuel are important 
in this connection. 

Clusters of small incendiary bombs must 
similarly be tested for satisfactory ballistics 
and proper functioning of the fuze which causes 
disintegration of the cluster. It must be deter¬ 
mined that the individual bombs will withstand 
the shock of being released from a cluster fall¬ 
ing at high velocity, will not function pre¬ 
maturely in the air, will fall in true flight, and 
will be dispersed in a satisfactory pattern of 
impact on the target area. 

The complete testing program, throughout 
development and manufacture, involves a host 
of tests which are applied to the various com¬ 
ponents of the bomb as well as to the complete 
munition. In this chapter the discussion will be 
chiefly concerned with tests that pertain to the 
penetration, functioning, and incendiary action 
of the bombs. 

Simple Tests for Functioning and Penetra¬ 
tion. Small incendiary bombs usually have an 
inertia type fuze, so that they will function 
when dropped from a specified minimum height, 
or when clamped in a pendulum and made to 
swing against a vertical surface. The former 
test is often used to determine the safe height 
from which a bomb may be dropped without 
functioning and the additional height from 
which functioning is certain to occur. The 
bombs may be dropped down a tube, or, if it is 
desired to test the functioning of an all-ways 
fuze, they may be dropped at random behind a 
safety barrier. The pendulum test is a safe and 
convenient method for tail-ejection bombs, since 
the bomb is securely held and pointed in a 
definite direction. 

The ability of bombs to withstand impact on 
a hard surface and function reliably is often 


53 


54 


TESTING AND EVALUATION OF INCENDIARIES 


tested by dropping them singly from a small 
airplane onto a concrete slab from an altitude 
of 1,000 ft. If the bombs are thrown out at 
random, a good indication of their inherent 
flight stability can be obtained by noting 
whether they quickly assume a condition of true 
flight or whether they yaw, tumble, or spin. 

The use of an air gun permits the horizontal 
projection of a bomb at any desired velocity, 
and has proved to be of great value in testing 
both the functioning of small bombs and their 
ability to penetrate various roof sections. Com- 


denced by the photographs of shots from the 
air gun. 

The air gun also is admirably suited to pene¬ 
tration tests, because of the convenience with 
which the gun can be loaded and the various 
simulated roof slabs can be mounted, since the 
entire setup is on the ground and readily acces¬ 
sible. Similar penetration tests can be con¬ 
ducted with a vertical mortar mounted above 
the test slabs. Because of the importance of the 
vertical mortar its use will be discussed in the 
section which follows. 



Figure 1. Diagram of mortar and chronograph arrangement for firing incendiary bombs. 


bined with high-speed movies, this technique 
was employed by the Chemical Warfare Service 
in the development of the M74 bomb, in which 
it was desired that the gel be ejected within 
8 ft of the first surface penetrated by the bomb, 
so as to be deposited in the attic or upper story 
of a Japanese dwelling. The speed of action of 
the fuze and ejection charge were varied until 
the desired functioning was attained, as evi- 


Mortar Tests. A vertical mortar, mounted on 
a tower above a test building, has advantages 
which make it one of the most useful and ver¬ 
satile tools for the testing and evaluation of 
incendiary bombs. Figure 1 shows a schematic 
diagram of an early mortar; improved models 
were developed and used later. When employed 
in tests with full-scale rooms and buildings, the 
downward flight of the bomb is to be preferred; 















































INTRODUCTION 


55 


it simulates the approach of a bomb released 
from high altitude, and gives data on penetra¬ 
tion, functioning, and incendiary action which 
correlate well with data obtained in airborne 
tests and actual incendiary raids. With a mortar 
suitably mounted on a movable support, it is 
possible to fire bombs through every part of a 
roof and to repeat the shots until an adequate 
basis has been established for drawing firm 
conclusions from the data. No such control of 
the point of impact of the bomb is possible in 
airborne tests, in which conclusions must often 
be based on a limited number of hits on the 
target. 

A mortar is equally suitable for tests with 
industrial targets. Bombs can be fired directly 
into such wooden targets as work benches, 
stacks of packing cases, bins, and can be fired 
into adjacent locations to determine the radius 
of action of a bomb that penetrates into a fac¬ 
tory without scoring a direct hit on combus¬ 
tibles. 

In the case of a bomb like the M74, which 
functions immediately after penetrating a light 
roof and ejects gel while the bomb is still in 
motion, mortar shots provide the only accept¬ 
able method of performing tests to determine 
the chance that the bomb will deposit gel in a 
location favorable for setting fire to combustible 
objects. 

With a bomb like the M69, the terminal ve¬ 
locity of which in free fall can be measurably 
controlled by varying the length of the cloth 
tail streamers, mortar tests can indicate the 
velocity that will give a desired degree of pene¬ 
tration through roofs, and the length of the 
streamers can be adjusted accordingly. 

Details such as the strength of the case and 
of the fuze to withstand impact on hard sur¬ 
faces can be tested with the mortar, as also can 
the sensitivity of the fuze needed to give reliable 
functioning upon hitting a very light roof. From 
accumulated experience it appears that future 
testing of small incendiaries should concentrate 
on tests in which the bombs are fired from a 
movable mortar into full-scale rooms and build¬ 
ings, both domestic and industrial, where type 
of roof, floor and occupancy could be varied to 
include all cases likely to be encountered in 
actual attacks. Airborne tests would be em¬ 


ployed to determine satisfactory performances, 
aimability, dispersion patterns on the target 
area, and general ballistic properties, for which 
no incendiary targets would be required. A 
final airborne test employing full-scale target 
buildings would serve as an overall check on the 
readiness of the bomb for standardization and 
operational use. 

Evaluation of Incendiary Effectiveness. First 
of all the necessary improvements were made 
in design, development, and manufacture to 
ensure satisfactory mechanical properties of the 
bomb, and when at last the bomb was dropped 
onto a combustible target, the sole utility of the 
incendiary lay in its ability to start a fire. It was 
natural therefore that much of the early experi¬ 
mental work was directed toward the inherent 
incendiary power of fuels. Small-scale labora¬ 
tory tests sufficed to indicate a relative order of 
merit among the fuels whose availability and 
low cost made them otherwise attractive. As 
experience indicated the profound effect of the 
nature of the target on the incendiary results 
obtained in tests, larger and more elaborate tar¬ 
gets were employed. Full-scale rooms and build¬ 
ings were finally used, in order to obtain data di¬ 
rectly applicable to the design and development 
of the kind of bombs that would be effective 
against enemy targets. 

Because of the great number of factors that 
influence the results obtained in incendiary 
testing, it is of the highest importance that all 
conditions of the experimental work be con¬ 
trolled. This is true despite the lack of any such 
control over enemy targets; absence of such 
control can reverse the relative performance of 
two munitions differing enough in merit to 
make the right choice important. Adequate 
ventilation with exclusion of drafts, control of 
wood moisture content, and careful placement 
of the fuel in a definite position are among the 
factors that must be controlled. Static place¬ 
ment of fuel will often give results quite differ¬ 
ent from those obtained when fuel is ejected 
from a bomb. It is apparent that no single 
simple target is adequate for the purpose of de¬ 
termining the incendiary merit of bombs for 
all uses. Some targets are more responsive to 
heat transferred by convection from flame and 
hot gases, while others respond better to radiant 



56 


TESTING AND EVALUATION OF INCENDIARIES 


heat. Only by use of a series of simple targets 
can the relative effectiveness of bombs be de¬ 
termined, and their absolute effectiveness can 
only be gauged by tests which involve full-scale 
target structures and which duplicate other 
conditions obtained in the enemy targets. 

Even with the utmost care in performing 
controlled experiments there is enough varia¬ 
tion in the results to require that tests be re¬ 
peated until sufficient data are obtained to ex¬ 
press the probability that a fire will be started 
under the given conditions. 


•^ 2 SMALL-SCALE LABORATORY TESTS 
Introduction 

The burning trials classified as small-scale 
tests are those which employ small structures 
of major dimensions under 2 ft. These struc¬ 
tures are usually arbitrary arrangements of 
pieces of wood, and do not necessarily imitate 
combustibles occurring in a dwelling or factory. 
The tests are of some value in determining the 
relative merits of various fuels, and were used 
in early work to select the most promising in¬ 
cendiary fuels from among those available. 

In developing a target suitable for a relative 
evaluation of fuels, the combustibility of the 
structure is first adjusted so that it will react to 
reasonable amounts of the fuels to be compared. 
This is accomplished by using a quantity of fuel 
which can be weighed or measured with ade¬ 
quate precision and which will burn for a rea¬ 
sonable time, and by conducting preliminary 
trials in which the dimensions and arrange¬ 
ment of the wood are varied until it is found 
that the target is sufficiently vulnerable to at¬ 
tack. Targets which are so resistant that any of 
the fuels will only char the surface slightly, or 
targets which are so combustible that a very 
small amount of fuel will cause complete burn¬ 
ing, are not useful. 

Since various types of targets react differ¬ 
ently to heat transferred by radiation or by 
convection, the disposition of the combustible 
surfaces with respect to the fuel warrants con¬ 
sideration in the choice of a target for small- 
scale tests. If a target consists of vertical sur¬ 


faces placed near but not touching the fuel, it 
will be most susceptible to radiant heat, whereas 
a vertical target in contact with the fuel, or one 
constructed of horizontal surfaces supported at 
some distance above the fuel, will be attacked 
most effectively by flame and hot gases rising 
from the fuel. A reversal of the apparent rela¬ 
tive effectiveness of two dissimilar fuels may 



setup. 

therefore take place if tests are carried out 
using two different types of targets. An ade¬ 
quate comparison of fuels may be made by em¬ 
ploying a target embodying both horizontal 
and vertical surfaces, or by separate tests using 
each type of surface. 

Description of Tests 

Harvard University This test 

arrangement, illustrated in Figure 2, was the 
























SMALL-SCALE LABORATORY TESTS 


57 





first incendiary test used in World War IL A 
3-oz fuel sample was placed in the center of 
the base, and the following data were recorded: 
time of aggressive burning, loss of weight after 
buffing off charred wood, and surface area at¬ 
tacked. This type of test served for early rough 
comparisons of incendiary materials, but as a 
rough gauge was little used after early 1942. 

Factory Mutual Vertical Strip Testp This 
test arrangement was even simpler than the 
previous one. It consisted simply of two wooden 
strips 24x2x% in., nailed to a wooden base 
8 x8x% in., and spaced at the top by a narrow 
strip of transite. A 30-g fuel sample was placed 
in the center of the base, and the loss in weight 
of base and uprights determined after burning. 

Factory Mutual Packing Case EndsP’^''"-^ 
This test setup consisted of a pair of wooden 
structures representing the ends of two ad¬ 
jacent packing cases. Figure 3 shows the ar¬ 
rangement and a typical burning test. This test 
was used primarily for testing sabotage in¬ 
cendiaries for which packing cases represent 
logical targets. 

University of Chicago Roof Section.^ This 
setup illustrated in Figure 4 was the first of 


9^:- X 2 X 


BAFFLE 


24 X 10 X 1 


Figure 4. University of Chicago roof-section test 
setup. Baffle on back is transite. 


the eaves, or half-attic type, although much 
smaller in size than those used extensively later 
on. The baffle shown was made of transite. Vari¬ 
ous incendiaries were placed in a standard 
position and comparative results observed quali¬ 
tatively. 


5 MINUTES 


8 MINUTES 


15 MINUTES 


Figure 3. Factory Mutual packing case ends. 
Test shown used 0.14-lb gasoline soaked in cellu- 
cotton. 
























58 


TESTING AND EVALUATION OF INCENDIARIES 


Standard Oil Development Co. Temperature 
Measurement.^^ This test consisted of a struc¬ 
ture resembling the Harvard setup, but made 
of angle iron, supporting 8 thermocouples at 
various distances from a sample of fuel burning 
in a pan on the base. The test showed the 
superiority of gasoline gels to either liquid 
gasoline or to heavy oils in that they maintained 
the highest temperatures for the longest times. 
This test was useful in the early stages of de¬ 
velopment of the AN-M69 incendiary bomb. 

Texas Company Coryier-Burning Tests. 
This test, illustrated in Figure 5, is simply a 



Figure 5. Texas Co. corner-test setup. 

wooden corner, 8x8x8 in., in which a 100-g fuel 
sample is burned and temperatures recorded 
by a thermocouple placed 5 in. above the base 
and 1 in. from each vertical board. The time- 
temperature curves obtained were quite useful 
in a preliminary comparison of incendiary 
fuels, and they showed a worthwhile correla¬ 
tion with later larger-scale tests. Loss in weight 
of the structure also was determined. Some of 
the interesting conclusions indicated were (1) 
cellucotton-bodied fuels were superior to jellied 
fuels, (2) turpentine and toluene were superior 
to gasoline, (3) fortifying agents such as mag¬ 
nesium powder and ammonium nitrate were 
valuable additives. 

Discussion 

The necessity of close control of all variables 
affecting burning became apparent in the small- 


scale evaluation tests. After the dimensions of 
the target had been fixed, such factors as the 
kind of wood, moisture content, draft, gel con¬ 
sistency, area of burning fuel, placement of 
fuel with respect to target, and the amount and 
particle size of additives in the fuel, were shown 
to have an influence on the burning of the tar¬ 
get. 

Small-scale tests proved useful in demon¬ 
strating the value of some oxidizing agents in 
improving the burning characteristics of the 
jellied fuels. Although oxygen is preferably 
drawn from the air rather than carried with the 
fuel, the time of aggressive burning of the fuels 
and their capacity for destroying the small tar¬ 
gets was increased by addition of small quanti¬ 
ties of oxidizing agents. The shortened total 
burning time still permitted destruction of the 
small-scale targets, but tests on larger and more 
difficult targets indicated the need for longer 
burning fuels. 

The advantage of small-scale tests lies in 
their simplicity. Their value appears to be 
limited to selecting the more promising fuels 
for further study on a larger scale. Careful 
choice of the target and good control of all 
experimental variables must be exercised if 
the results of small-scale tests are to have any 
significance. Small differences among fuels sub¬ 
jected to small-scale tests should be disre¬ 
garded, and more adequate test methods should 
be employed (see Sections 3.3 and 3.4). 


3 3 LARGE-SCALE LABORATORY TESTS 

Introduction 

Since the results of incendiary tests are func¬ 
tions of the targets used as well as of the in¬ 
cendiaries tested, results are of doubtful value, 
unless a careful simulation of targets of prac¬ 
tical interest is made. Accordingly, the small- 
scale tests used early in World War II were 
soon replaced by tests on structures simulating 
actual targets such as parts of houses and com¬ 
bustible contents of factories. These test targets 
usually had a minimum dimension of at least 

4 ft. Vertical tongue-and-groove wooden par¬ 
titions, whole or half-attics, factory work- 






LARGE-SCALE LABORATORY TESTS 


59 


benches, stacks of packing cases, etc., were used 
as representative targets. 

Large-scale tests are useful for determining 
the relative incendiary values of fuels and for 
testing incendiary bombs. With proper design 
of targets and control of experimental condi¬ 
tions, large-scale laboratory tests can go a long 
way toward establishing the absolute incendi¬ 
ary effectiveness of a bomb or quantity of fuel 
on the structures tested. In such tests many 
factors that influence the burning of a target 
become less critical than they are in small-scale 
tests, and therefore the results are more con¬ 
sistent and give a reasonably good indication 
of the incendiary action that may be expected 
in actual attacks. Such large-scale tests, util¬ 
izing a mortar to shoot bombs downwards 
onto the targets, can give answers to all the 
variables of penetration, functioning, and fire 
starting, except the final answer involving 
the ballistic properties and flight stability of 
the bombs, for which airborne tests are re¬ 
quired. However, intelligent application of the 
principles of large-scale laboratory testing can 
reduce the requirements for airborne testing to 
a minimum. 

Tests may be conducted by placing bombs or 
weighed quantities of fuels in definite positions 
in relation to the test structures, by causing 
bombs to eject fuel against or into the test 
structures, or by shooting bombs down onto the 
test structures from a mortar. When such tests 
are carried out with a variety of structures 
which are faithful replicas of enemy targets, 
they serve to establish the optimum quantity of 
fuel and hence, the required size of bomb to 
destroy such targets. The following sections 
describe the principal test arrangements used, 
representing both domestic and industrial tar¬ 
gets. 


Standard Oil Development Co. 

Half-Attic Structures 

The prototype of this category of test struc¬ 
ture is the half-attic structures designed and 
used by the Standard Oil Development Co. in 
the winter of 1941-42. The design shown in 
Figure 6 had 2x4-in. joists on 16-in. centers 


with 1-in. boarding below the joists. Other 
designs used were similar to the one illustrated, 
but with 1-in. floor boards above the joists, or 
with a lath and plaster ceiling below the joists. 
Still others had 2x6-in. joists on 24-in. centers. 
The roof section of rafters, battens, and transite 
baffle was similar in all cases. 

Fuel was placed statically at definite distances 
from the eaves line, or was ejected into the 
eaves. The principal data recorded were (1) 
whether a destructive fire was obtained or not, 
(2) the time taken by the structure to collapse, 
and (3) the time the fire reached the low point. 



Figure 6. Standard Oil Development Co. half¬ 
attic test structure. 


Tests in these structures showed clearly the 
advantage of gel fuels over liquid gasoline or 
heavy oils. The efficiency of the tail-ejection or 
target-seeking principle also was clearly demon¬ 
strated. A great deal of the mechanism of fire 
starting was learned in these tests; namely, the 
importance of reinforcing radiation from two 
burning surfaces or of two pieces of fuel. An 
important result observed was a quantitative 
relationship between the distance from eaves 
line and the weight of gel required to start a 
destructive fire. This relation is illustrated in 
Figure 7, which shows that for the structure 
used 10 lb of gel are required at 3 ft from the 
















60 


TESTING AND EVALUATION OE INCENDIARIES 


eaves, 20 lb at 4 ft, etc. The tests showed that 
for this type of structure, gasoline gel was 
slightly superior to magnesium and greatly 
superior to therm-8. Tests on these structures 
were remarkably reproducible, although con- 



0 1 2 3 4 5 6 7 


DISTANCE FROM EAVES IN FEET 

Figure 7. Relationship between fuel charge re¬ 
quired to produce a destructive fire and the dis¬ 
tance from the eaves. 

sideration had to be given to wood species, wood 
moisture .content, ambient temperature, and 
other factors. 

Tests with the half-attic structures were of 
vital importance in the development of the 
AN-M69 incendiary bomb. The tests outlined 
above gave assurance that the bomb would 
contain enough fuel to be an effective in¬ 
cendiary. 


Factory Mutual Half-Attic 
Test Structures^’ 

The Factory Mutual group employed a struc¬ 
ture which was quite similar to that used by 
Standard Oil Development Co., the main dif¬ 
ference being that it was somewhat more diffi¬ 
cult to ignite. It was set up inside a specially 
constructed wooden room, which in turn was 
enclosed by a noncombustible building. With 
these precautions there was relative freedom 
from drafts, and the confinement of heat and 


radiation from surrounding surfaces simulated 
the conditions that would normally be found in 
small rooms. This structure was primarily used 
in the early stage of development of the E19 
bomb. 

In an endeavor to develop a single target that 
would prove adequate for the evaluation of 
small bombs, about 10 small attic-type structures 
were devised and used in tests. It was concluded 
that no single target was entirely satisfactory, 
but for small magnesium bombs excellent re¬ 
sults were obtained with a half-attic structure 
having a floor 2 ft sq and a sloping-roof section 
2x4 ft set at an angle of 60 degrees to the 
horizontal (Figure 8). When made of 1-in. 
boards, it has a suitable response to the initial 
flame and residual radiant heat from small 
magnesium bombs having different incendiary 
fillings to reveal second-order differences. 


3.3.4 Factory Mutual Industrial 

Type Targets'^’ 

The Factory Mutual Research Corporation 
was the first NDRC contractor to become inter¬ 
ested in fire starting in industrial rather than 
domestic occupancies. The principal targets 



Figure 8. Factory Mutual small half-attic test 
structure. 


with which they worked were a light work¬ 
bench, a heavy workbench (Figure 9), a section 
of tongue-and-groove wooden partition (Figure 
10), and pairs of packing case ends (see Sec- 










































LARGE-SCALE LABORATORY TESTS 


61 



Figure 9. Heavy workbench-incendiary test struc¬ 
ture. Test shown was made with gasoline soaked 
in cellucotton. 


Figure 10. Tongue-and-groove wooden partition 
test structure, showing test with four M52 in¬ 
cendiary bombs. 
























62 


TESTING AND EVALUATION OF INCENDIARIES 



Figure 11. Factory Mutual radial incendiary- 
test structure, closed-center, 8-panel type. 

tion 3.2). Tests were made on these four targets 
with various fuels and bombs at different dis¬ 
tances. The relative impotence of the 4-lb mag¬ 
nesium bomb against most of these targets and 
the equivalence of gelled and cellulose-bodied 
fuels were among the significant conclusions re¬ 
sulting from these studies. 

In an attempt to develop a universal in¬ 
cendiary target, Factory Mutual designed some 
radial targets of the type shown in Figure 11. 
These did not represent any actual targets, but 
it was thought that they could be calibrated in 
terms of various actual targets, and thus be 
useful as a universal yardstick of incendiary 
merit. While the idea was interesting, it proved 
to be too awkward and too far from reality to 
be greatly useful. 


* Incendiary Evaluation Project 

Industrial Targets^® 

The Incendiary Evaluation Project group at 
Edgewood Arsenal extended the Factory Mu¬ 
tual work on industrial targets in an extensive 
series of tests on five typical combustible ob¬ 
jects usually found in factories, viz., light 
workbenches with tote box underneath, vertical 
storage bins, vertical tongue-and-groove par¬ 
titions, stacks of eight packing boxes, and cor¬ 
rugated cardboard cartons, all of which are 
illustrated in Figure 12. These targets were 
finally chosen as being representative after 
inspection of a number of industrial plants. The 



workbench 


Figure 12. Industrial targets for incendiary test¬ 
ing used by the Incendiary Evaluation Project at 
Edgewood Arsenal. 


targets were constructed of two kinds of wood, 
1-in. Douglas fir for the workbenches, storage 
bins and partitions, and 1-in. Sitka spruce for 
the tote boxes and packing cases. 

Tests were carried out with the AN-M69, 
AN-M50, and M74 bombs by firing the bombs 
from the mortar downwards onto or near the 
targets. It was possible to substitute statically 
placed bombs for part of the tests on the M50 
and M69, but in the case of the M74 all tests 
had to be made with the mortar in order to 
simulate the true action of the M74. The results 
are described in the following sections. 

AN-M69 Bomb. 1. The total length of travel 
of the gob of gel in an ejection along the floor 
(unobstructed) is 100 ft. 
































LARGE-SCALE LABORATORY TESTS 


63 


2. If the gob strikes normal to a smooth 
vertical surface, or within 30 degrees of the 
normal, the gob sticks against the surface. 

3. If the gel strikes a smooth vertical surface 
at an angle greater than 30 degrees to the nor¬ 
mal, it is deflected at an angle of approximately 
5 degrees and then travels for an average dis¬ 
tance of 15 ft. 

4. When the bomb lands directly in a stack 
of cardboard cartons, wooden packing cases, or 
in a storage bin, a fire will always be started. 

5. When the gel strikes the side of a stack of 
cardboard cartons at any angle, sufficient gel 
will remain on the cartons to cause a fire. 

6. If the gel strikes the side of a stack of 
wooden packing cases at an angle within 60 
degrees of the normal, a fire is started. 

7. When the gel strikes the vertical tongue- 
and-groove partition at an angle of 30 degrees 
to the normal or less, the chance of starting a 
fire is 0.63 if some other combustible, such as 
cardboard cartons, boxes, etc., is present im¬ 
mediately behind the partition to provide re¬ 
radiation for the flame on the back side. If 
the gel sticks at a point where no other members 
which will support fire are present, or if the gel 
rebounds from the surface, a negative result 
is obtained with the partition. 

8. If the bomb lands directly in a tote box 
under a workbench, the ejection will blow the 
gel from the box without setting it afire, and the 
probability of a fire becomes the same as if the 
bomb hit on an open floor. 

9. If the gel strikes the side of a tote box 
under a bench at an angle of 30 degrees to the 
normal or less, the gel sticks and a fire is 
started. When striking at angles over 30 de¬ 
grees to the normal the gel rebounds and a 
negative result is obtained. (The legs of the 
benches are assumed not present.) 

10. If the gel strikes the open side of a stor¬ 
age bin at any angle, a fire is started. When gel 
strikes the end of a bin at an angle of 30 
degrees or less to the normal, the gel will stick. 
At greater angles it rebounds, but when it 
sticks, the chance of starting a fire is 0.63. 

AN-M50 Bomb. 1. If the bomb lands directly 
in a stack of cardboard cartons, wooden pack¬ 
ing case, storage bin, or tote box under a 
bench, a fire will always be started. 


2. If the bomb lands within 9 in. of a stack of 
cardboard cartons, the radiation and glowing 
sparks will cause a fire. The distance of 9 in. 
is the maximum for 100 per cent probability of 
fire. At greater distances up to 4 ft, the bomb 
gives lower probabilities of destruction. 

3. If a bomb lands outside of a stack of 
wooden packing cases, even if directly against 
the side, no fire results. 

4. If the bomb lands outside of the tote box 
under a bench, even if against the side of the 
box, a negative result is obtained. 

5. If the bomb lands within 2 in. of the 
vertical tongue-and-groove partition at a point 
where some other combustible is at the back 
side, a fire is started. If no other fire-supporting 
surface is present, or if the bomb is at a greater 
distance from the partition, no fire results. 

6. If the bomb lands immediately in front of 
the open compartments of the storage bin, a 
fire is started, but at any greater distance, nega¬ 
tive results are obtained. If the bomb is within 
2 in. of the partition forming the end of the 
bin, a fire vdll result. 

M7Jf- Bomb. 1. If the gel from an M74 lands 
on top of a stack of cardboard cartons, or hits 
the side of the stack, or lands on the floor within 
12 in. of the side of a stack, a fire is always 
started. 

2. When the bomb is yawed and the gel lands 
on top of a stack of wooden packing cases, the 
chance of starting a fire is 0.93. If the gel 
strikes the side of the stack, the probability 
of starting a fire is 0.59. When gel lands on 
the floor within 5 in. of the side of the stack, a 
fire will always be started. 

3. If the gel from an M74 bomb hits the side 
of a vertical tongue-and-groove partition at a 
point where some other combustible is at the 
back side, the chance of starting a fire is indi¬ 
cated to be approximately 0.60. When gel lands 
on the floor within 8 in. of the partition, a fire 
will always be started. If no other fire-support¬ 
ing surface is present, or if the gel lands at a 
greater distance from the partition, no fire 
results. 

4. When the gel from an M74 lands on top 
of a storage bin, the probability of starting a 
fire is 0.75. When the gel strikes the shelves on 
the open side of the bin, or on the floor within 




64 


TESTING AND EVALUATION OF INCENDIARIES 


6 in. of this side, a fire may always be expected. 
If the gel strikes the end of the bin, the chance 
of starting a fire is assumed to be the same as 
that for gel hitting the matched partition, or 
0.60. Finally, when gel lands on the floor within 
8 in. of the end of the bin, a fire will always be 
started. 

5. If the gel from an M74 lands on top of a 
workbench, it burns harmlessly without effect 
other than to burn a hole through the bench top. 
When the gel strikes the side of the tote box 
under the bench, or on the floor within 6 in. 
of the side of the box, a fire is always started. 

These conclusions do not cover all possibili¬ 
ties that could be envisioned, but they indicate 
the general order of fire-starting probabilities 
for each combination of bomb and target. In 
the next section these results will be combined 
into an analysis of the probability of starting 
a fire in a given factory. 


Application of lEP Tests to a 
Model Factory Target 

Incendiary tests of the kind described in the 
previous section answer the question whether 
a given incendiary will start a fire in a given 
position relative to a combustible object in a 
factory. In order to combine these isolated re¬ 
sults into the overall probability of starting a 
fire in a factory, a model factory layout was 
made and calculations carried through for each 
type of bomb. The factory layout used contained 
the five combustible objects which have been 
used in the burning experiments: namely, 
workbenches, storage bins, wooden partitions, 
wooden packing cases, and cardboard cartons. 
Other combustibles such as trash, oil, and waste, 
may be present in an actual factory, but their 
quantities are unknown; therefore they were 
ignored in this calculation. Experimental work 
has dealt primarily with initiation of fires in 
targets without regard to the probability of 
spreading fires; hence the analysis given here 
indicates only the probability of starting a fire 
—not of its spreading or destroying the factory. 

Description of Model Factory. The factory 
layout is shown in Figure 13. Stacks of card¬ 
board cartons and wooden packing cases, each 


15 ft high, are present in the receiving and 
shipping section. One workbench with tote box 
is also present in this section. In the main work¬ 
ing section are 16 benches plus tote boxes, and 

16 storage bins, each 10 ft high, placed back to 
back. A vertical tongue-and-groove partition, 
extending to the roof (20 ft), separates the two 
sections. The total combustible floor loading is 
24.8 per cent, distributed as follows: 

Area, sq ft % of total floor area 


Cardboard cartons 

136 

4.9 

Wooden packing cases 

127 

4.5 

Workbenches 

319 

11.4 

Storage bins 

108 

3.9 

Vertical partitions 

3 

0.1 


693 

24.8 


The total area of the factory is 2,800 sq ft. 

Analysis for M69 Bomb. The plant layout 
was first divided into 112 sections as shown in 
Figure 13. Each of these sections was then 
further divided into nine equal subsections, so 
that a total of 9x112 or 1,008 separate areas 
were created. In order to minimize the number 
of points required for analysis, one out of each 
group of nine subsections was chosen accord¬ 
ing to a table of random numbers, and the prob¬ 
ability of starting a fire if a bomb came to rest 
in the center of each of these areas was deter¬ 
mined. An earlier analysis of the factory layout 
using 1,681 separate points yielded the same 
overall probability of starting a fire as found 
by the random number method. 

In order to find the probability of fire in each 
case, a measurement was made of the total 
angle within which a gob of gel ejected from an 
M69 would start a fire. The angle that was sub¬ 
tended by a surface from which the gel bounced 
to a combustible object was counted as part of 
the total angle in which a fire could be started. 
The probability of starting a fire was then de¬ 
termined by dividing the angle within which 
fires would be initiated by 360 degrees. In order 
to show the contribution of each target in the 
factory to the overall probability, separate 
totals were kept for each of the various com¬ 
bustibles. 

A sample calculation is here given for point 
No. 58 (Figure 13) to illustrate the method 
used in obtaining the data. By use of a trans¬ 
parent overlay, the angles subtended by the 



LARGE-SCALE LABORATORY TESTS 


65 


various combustible objects and within which 
gel will stick and cause a fire, are determined. 
The total effective angles subtended for each 
type of target within range of point No. 58 
are as follows. 


Tote boxes under benches 55° 

Storage bins (open sides) 70° 

Storage bins (ends) 55° 

Wooden partitions (side) 25° 

Cardboard cartons (side) 5° 


The angles for all 112 points are averaged, 
and this average angle is divided by 360 degrees 
to obtain the probability of gel from an M69 



Figure 13. Plan view of model factory used for 
estimation of incendiary-bomb effectiveness. 


bomb hitting a particular target. If this prob¬ 
ability is then multiplied by the probability of 
starting a fire in the particular target under the 
conditions, the overall probability of starting 


fires in this target is obtained. The sum of these 
probabilities for all types of targets then gives 
the overall probability of starting fire in the 
factory. For the M69 bomb the final probabili¬ 
ties of fire starting were calculated to be as 
shown below. 


Tote boxes under benches 

0.126 

Storage bins 

0.141 

Wooden partitions 

0.018 

Packing- cases 

0.086 

Cardboard cartons 

0.113 


Total 0.484 


Thus an M69 bomb dropped at random into 
this factory has a 0.484 probability of starting 
a fire. 

Analysis for M50 Bomb. Since no complete 
data are as yet available on the nature of the 
bouncing which occurs when an M50 strikes 
the floor of a factory, the analysis has been 
carried out assuming that the bomb stays where 
it lands. The probability of starting a fire is 
then merely the ratio of the area within which 
the M50 is effective to the total area. The area 
within which the M50 is effective is made up 
of two parts: (1) The area of the combustibles 
within which the M50 will start a fire, and (2) 
a small strip of area around these combustibles 
wherein the bomb will cause a fire. If it is 
assumed that the bomb does bounce an ap¬ 
preciable distance, the probability of fire is 
increased somewhat over the values shown, 
although even if the bomb bounces against 
some of the targets (wooden packing cases and 
tote boxes under benches), no fire is obtained. 

Applying the same approach as used for the 
M69 bomb, the final probabilities of fire start¬ 
ing for the M50 bomb were calculated to be the 
following: 


Tote boxes under workbenches 

0.023 

Storage bins 

0.040 

Wooden partitions 

0.001 

Packing cases 

0.045 

Cardboard cartons 

0.065 

Total 

0.174 


Thus an M50 bomb dropped at random into this 
factory has a 0.174 probability of starting a 
fire. 

Analysis for M7Jf Bombs. It is known that 





















































































































66 


TESTING AND EVALUATION OF INCENDIARIES 


s 



Figure 14. Comparison of vertical and 26° oblique 
views of storage section of model factory, for use 
in estimating hits by M76 incendiary bomb. 


M74 bombs ordinarily yaw so that the gel 
charge descends at an angle, with the result 
that the gel and the case do not follow the 
same path. A study of the gel paths of M74 


bombs dropped on the prototype factory build¬ 
ing at Edgewood Arsenal led to the conclusion 
that 26 degrees from vertical was a good aver¬ 
age angle of descent for the gel charge from 
M74 bombs. 

The analysis for the M74 bomb is similar to 
that for the M69 bomb, except that the circular 
distribution of hits from a given point involves 
three dimensions instead of two dimensions, as 
with the M69. Since a complete integration 
around 360 degrees proved to be quite laborious, 
the problem was simplified by taking shots from 
16 evenly spaced directions at intervals of 221/2 
degrees. Perspective drawings were made of 
the factory from 16 directions, all at an angle 
of descent for the gel charge of 26 degrees. As 
an example. Figure 14 shows the comparison 
of the plan view and 26 degrees perspective 
view of a section of the factory. The vulnerable 
exposed areas are shown shaded. The shaded 
areas of these views projected onto the hori¬ 
zontal plane are a measure of the probability 
of an M74 bomb projecting its gel charge 
against a combustible surface. The analysis for 
the M74 bomb was made in terms of 16 direc¬ 
tions instead of 112 points, and the analysis was 
kept separate for each target type as before. 
If the vulnerable areas of each type of target 
are multiplied by the respective probabilities 
of starting a fire, the overall probability of 
starting a fire in this type of target is obtained. 

The final probabilities of fire starting for the 
M74 bomb were calculated to be the following: 


Tote boxes under workbenches 

0.011 

Storage bins 

0.052 

Wooden partitions 

0.018 

Packing cases 

0.051 

Cardboard cartons 

0.070 

Total 

0.202 


Thus an M74 bomb dropped at random into this 
factory has a 0.202 probability of starting a 
fire. The M74 loses efficiency by the nearly 
vertical descent of its gel and the inability of 
the gel to break through 1-in. board surfaces 
when it hits them. 

Discussion of Results. Table 1 summarizes 
the results given in the above sections, with 
two additional variables, the length of time for 
fires to become self-sustaining and the number 

































































LARGE-SCALE LABORATORY TESTS 


67 


Table 1. Probability of fire starting in model factory layout. Number given equals fractional number of functioning 
bombs penetrating to interior of factory building which start fires capable of consuming the local target; called prob¬ 
ability of fire start, P/. 


M50 Bomb M69 Bomb M74 Bomb 

Self-sustaining within* Self-sustaining within* Self-sustaining within* 

3 min 10 min 40 min 3 min 10 min 40 min 3 min 10 min 40 min 


Fires which extend to roof 

Packing cases 0.045 

Cardboard cartons 0.065 

Matched partition .... 

Storage bins 0.039 

Subtotal (fires to roof) 0.149 

Fires which do not extend to roof 

Tote boxes under benches 0.023 

Total 0.172 


0.045 

0.045 

0.086 

0.086 

0.065 

0.065 

0.113 

0.113 

0.001 

0.001 



0.039 

0.030 

o.iii 

0.111 

0.150 

0.151 

0.310 

0.310 

0.023 

0.023 

0.126 

0.126 

0.173 

0.174 

0.436 

0.436 


0.086 

0.049 

0.051 

0.051 

0.113 

0.070 

0.070 

0.070 

0.018 


0.018 

0.018 

0.141 

0.021 

0.034 

0.052 

0.358 

0.140 

0.173 

0.191 

0.126 

0.011 

0.011 

0.011 

0.484 

0.151 

0.184 

0.202 


♦Time limit given is time within which fire grows to such proportion that incendiary material may be removed without fire going out. 


of fires which are likely to ignite the roof. This 
last point is important as analysis of attacks on 
German factories shows that a major damage is 
usually obtained if the roof is combustible and 
is ignited. All the targets are assumed to be 
capable of igniting a combustible roof, except 
workbenches, due to their low height. 

In preparing Table 1, time intervals of 3, 10, 
and 40 min were selected as being of interest in 
indicating the relative effectiveness of the 
bombs in starting quick fires. In Table 1 the 
values given in each column include the values 
for lesser times. Thus, for the M74, the chance 
that a bomb will produce within 40 min a fire 
that will eventually involve the roof is 0.191. 
Of this total chance, 0.140 is the chance of such 
a fire being established within 3 min. On ac¬ 
count of the probable importance of a quick¬ 
starting fire and the relatively great importance 
of starting a fire which ultimately reaches the 
roof, the chance of fire starting is so sub¬ 
divided. 

From Table 1, the following may be noted: 

1. For every 100 functioning bombs entering 
a factory layout such as that shown in Figure 
13, fires will be started as shown below. 

Fires that can eventually reach the roof 



Total 


Self-sustaining Self-sustaining 


fires 

Total 

within 10 min 

within 3 min 

M50 

17 

15 

15 

15 

M69 

48 

36 

31 

31 

M74 

20 

19 

17 

14 


2. For the number of bombs in a 500-lb 
aimable cluster, assuming penetration and 100 


per cent functioning in the factory layout, fires 
will be started as shown in the chart below. 

Fires that can eventually reach the roof 



Total 


Self-sustaining 

Self-sustaining 


fires 

Total 

within 10 min 

within 3 min 

M50 

19 

17 

17 

17 

M69 

18 

14 

12 

12 

M74 

8 

7 

6 

5 


For full details on the calculations and more 
detailed data see reference 8. 


Texas Company Panel TesP^ 

This test arrangement consists of plywood 
panels supported on a cement block wall (Fig¬ 
ure 15). The purpose of the test was to find 
the best incendiary filling for the E9 40-lb oil 
bomb. Accordingly, a mortar was built to hold 
the same volume of fuel as the bomb contained 
and to eject it in a manner that duplicated 
normal ejection from the bomb at rest. The 
ability of the various fuels tested to avoid ex¬ 
cessive breakup and to adhere to the target was 
observed. The percentage of the wooden panel 
destroyed within 10 min was adopted as the 
basis for comparing the incendiary merit of 
different fuels. 

Some conclusions reached in tests on this 
structure are as follows. 

1. An incendiary filling made up of units of 
a predetermined size is better than one the 
unit size of which is dependent on the ejection 
forces. 

2. The best filling is one which combines 










68 


TESTING AND EVALUATION OE INCENDIARIES 






Figure 15, Texas Co. panel test setup. Fire was extinguished in 10 min. 


Table 2. Penetrating power of small incendiary bombs. 


Normal striking velocity ft/sec 
AN-M69 M69X AN-M52 M7-1 AN-M50 E19 
Description of roof 230 245 325 420 420 600 


Metal sheeting, 20-26 gauge 

p* 

P 

0 

P 

P 

p 

Asbestos sheeting, 5 in. (6 mm) 

P 

P 

P 

P 

P 

p 

Wood planking, 1 in. (2.5 cm) 

P 

P 

P 

P 

P 

p 

Slate on wood sheathing 

P 

P 

P 

P 

P 

p 

Tile on wood battens 

P 

P 

P 

P 

P 

p 

Hollow tile slabs, 2^-3^ in. thick, with or without 2-5-in. cinder 
concrete for drainage 

P 

P 

P 

P 

P 

p 

Lightweight reinforced concrete (1,000 psi), in, thick, with or 

without 2-5-in. cinder concrete for drainage 

P 

P 

P 

P 

P 

p 

Reinforced structural concrete (3,000-4,000 psi), 3 in. thick 

NPt 

NP 

? 

P 

P 

p 

Heavy tile slab, 8 in. thick, with 2-5-in. cinder concrete for drainage 

NP 

NP 

NP 

P 

P 

p 

Reinforced structural concrete (3,000-4,000 psi), 4 in. thick 

NP 

NP 

NP 

? 

? 

p 

Reinforced structural concrete (3,000-4,000 psi), 5 in. thick 

NP 

NP 

NP 

NP 

? 

p 

Heavy tile slab, 8 in. thick, with 2-in. reinforced concrete 

NP 

NP 

NP 

NP 

isp 

p 

Reinforced structural concrete (3,000-4,000 psi), 6 in. thick 

NP 

NP 

NP 

NP 

NP 

p 


mn 


*P = penetrates 

tNP = does not penetrate 




















TESTS IN FULL-SCALE ROOMS AND BUILDINGS 


69 


maximum heat of combustion with satisfactory 
burning characteristics. 

3. Rolls of cellucotton saturated with tur¬ 
pentine gave the best results, originating from 
the combination of high heating value of fuel 
and retention in large masses. 

4. Addition of furfural extract from lube oil 
refining to fuel mixture increases the heating 
value, while addition of powdered magnesium 
promotes more rapid burning. Both additions 
seem to be desirable. 

Penetrating Power of Bombs 

The vertical mortar setup at the Standard 
Oil Development Co. was utilized to make a sys¬ 
tematic study of the penetration, or perfora¬ 
tion, of domestic and industrial roof types by 
small incendiary bombs. Sections of various 
roof types were constructed and placed under 
the mortar in a horizontal or pitched position, 
depending on the roof type, and then subjected 
to test by bombs at their normal striking veloci¬ 
ties. The bombs tested in this manner included 
the AN-M50, AN-M52, AN-M54, AN-M69, AN- 
M69X, and M74. The AN-M52 and E19 bombs 
were tested by similar technique at the Factory 
Mutual Research Corporation. The data ob¬ 
tained are summarized in Table 2. 

3 ^ TESTS IN FULL-SCALE ROOMS AND 
BUILDINGS 

Introduction 

Tests in full-scale rooms and buildings sur¬ 
pass all others in significance because the data 
can be applied directly in estimating the results 
to be expected in actual incendiary raids. Air¬ 
borne tests permit an evaluation of the overall 
performance and incendiary effectiveness of 
the bomb, and are therefore to be conducted in 
the late stages of development and as service 
tests prior to standardization. However, all 
essential information regarding penetration, 
performance, and fire-starting ability can be 
obtained from mortar shots where bombs are 
fired downward into the structures. In such 
tests the bomb can be delivered through any 
desired part of the roof, and it is not necessary 
to employ the extensive array of targets that 


are needed to get a reasonable percentage of 
hits in airborne tests. It is believed that future 
test work should be concentrated on mortar 
shots into full-scale rooms and buildings, with 
a final minimum number of airborne tests as 
an ultimate check on overall performance. 

3.i.2 Tests at Huntsville Arsenal 

Among the earliest tests in full-scale build¬ 
ings were those conducted by the Chemical 
Warfare Service at Huntsville Arsenal in April 
1942. One- and two-story farm buildings of 
frame construction were used in static tests of 
the small magnesium and therm-8 bombs and 
the experimental 7-lb base-ejection oil bomb. It 
was reported that the AN-M54, AN-M50A1, 
and AN-M52 were of comparable effectiveness 
when fired statically in buildings of light con¬ 
struction. The small oil bomb was judged the 
most effective of the bombs tested, despite the 
observation that the burning fuel was easily 
extinguished. 

In airborne tests very few hits were obtained 
so that no conclusions could be drawn regarding 
fire-starting efficiency, but it was noted that 
the M50 and M54 had excessive penetration for 
this type of structure. 

Tests at Jefferson Proving Ground 

In July 1942 tests w^ere run by CWS and 
the Ordnance Department at Jefferson Proving 
Ground, with NDRC participation. Several 
groups of typical farm buildings were used as 
targets, and dropping tests were conducted 
with the M50 and M52 magnesium bombs, the 
M54 therm-8 bomb, a plastic incendiary bomb, 
the M47 oil bomb, and two sizes of small base- 
ejection oil bombs, weighing 4.8 and 6.2 lb, re¬ 
spectively. The objectives of the tests were to 
determine the relative merits of the various 
munitions. Data were obtained on stability 
in flight, penetration, functioning, incendiary 
effectiveness in structures, ability to set grass 
fires, number of duds and their cause, disper¬ 
sion pattern of clustered bombs, and ignition 
and dispersion of gel from the M47 bomb. The 
majority of the tests were conducted from 2,500 
ft altitude, with a few from 5,000, 10,000, and 
20,000 ft. 



70 


TESTING AND EVALUATION OF INCENDIARIES 


The flight stability of the M50 was found 
good, and its functioning and incendiary effec¬ 
tiveness satisfactory. The M54 had good flight 
stability and reliable functioning, but was not 
as good an incendiary as the M50. The M52 
showed marked instability in flight and poor 
functioning. However, it was considered to have 
promising incendiary properties for a bomb of 
its weight. The 6-lb oil bomb (M56, later M69) 


" ‘ ^ Tests by Standard Oil 

Development Co. 

The previous tests at Huntsville Arsenal and 
Jefferson Proving Ground had suffered from 
the usual difficulty of getting a desirable num¬ 
ber of significant hits in airborne tests. Fur¬ 
thermore, the buildings used as targets served 
only to establish a relative order of effective- 



MK. IV STARTS SLOW FIRE 
WHICH DIES WITHOUT 
attention (WINDOWS 
and doors CLOSED) 


Figure 16. Construction and summary of tests in Central German structure. 


was considered promising and superior to the 
5-lb bomb. It was recommended by CWS that 
development work to improve the M47, M56, 
M50, and M54 bombs be undertaken and that 
these bombs should be manufactured in quan¬ 
tity. NDRC observers concluded that the prin¬ 
ciple of delayed ejection of gel had been shown 
to have considerable merit. 


ness of the bombs. In order to obtain sufficient 
quantitative data on authentic structures, it 
was decided to conduct mortar tests on target 
buildings that would be exact reproductions of 
German houses. Three types of houses were 
designed and built, typical of Rhineland, Cen¬ 
tral German, and Eastern German construction. 
Tests with the Rhineland and Central German 

















































































TESTS IN FULL-SCALE ROOMS AND BUILDINGS 


71 


stiuctiires were completed prior to construction 
of the target village at Dugway Proving 
Ground, and constitute an important record of 
large-scale tests and demonstrations. Figures 
16, 17, 18 show the construction and typical 
tests in these structures. 



Figure 17. Outside view of incendiary test in 
Central German structure. 


Tests with Rhineland Structuresd-' The M50, 
M69, and M69X bombs were fired from a mov¬ 
able mortar, aimed at rafters and between 
rafters, and at points near the ridgepole and 
near the eaves. Inert bombs were used for pene¬ 
tration tests, and live M69 and M69X bombs 
were fired for performance. A limited number 
of fires were permitted to go to the point where 
the incendiary effectiveness of the bombs could 
be demonstrated. 

It was found that the M50 frequently pene¬ 
trated the roof and the attic floor when no 
rafter was encountered. The M69 did not pene¬ 


trate through the attic floor when fired at its 
normal terminal velocity of 225 ft per sec. A 
substantial proportion of the M69X bombs, 
fired at 270 ft per sec velocity, penetrated 
through the roof and attic floor. Satisfactory 
performance of the M69 after penetrating the 
roof was demonstrated, and it was determined 
that if from one-third to one-half of the gel is 
ejected into the eaves the M69 will start a de¬ 
structive fire in these structures. However, it 
was shown that neither the M50 nor the M69 
will start destructive fires in a typical Rhine¬ 
land attic if the incendiary contents are more 
than 4 to 5 ft from the eaves. 



Figure 18. Penetration of M69X bomb in Ger¬ 
man structure. 


Tests in Central German Structures.-^ The 
M50, M69, and M69X bombs were used in tests 
similar to those performed with the Rhineland 
structures. The Central German structure had 
a tile-on-batten roof instead of the slate-on- 
sheathing roof generally found in Rhineland 























72 


TESTING AND EVALUATION OF INCENDIARIES 


structures. Data on penetration, functioning, 
and fire-raising power were obtained. Bedroom 
furnishings were placed in the room below the 
attic floor, to test the incendiary capacity of 
the M50, which often penetrates to that level. 
Particular attention was paid to the moisture 
content of the structures, tests for destruction 
being performed only when the moisture con¬ 
tent was not lower than 10 to 12 per cent. A few 
tests were run with moisture content in the 
range of 20 to 25 per cent. 

It was found that the tile roof offered the 
major resistance to the M69 bomb, little differ¬ 
ence in ultimate penetration being found as the 
shots progressed towards the eaves line. Ap¬ 
proximately 25 per cent of the M69 bombs re¬ 
mained sticking upright into the attic floor, 
none penetrating through the floor. 

The penetration of the M50 was dependent 
on the position where the bomb came through 
the roof. When entering near the ridge, all 
M50’s remained in the attic; in the middle of 
the roof from 21 to 40 per cent of the bombs 
penetrated through the attic floor, depending 
on the velocity at which they were fired. Near 
the eaves, all bombs penetrated the attic floor, 
14 per cent of them at higher velocities pene¬ 
trating two floors below the attic. 

Tests with live bombs showed that the M69 
and M69X started rapidly destructive fires 
when the fuel charge was ejected into the eaves 
of the attic. No bomb (M50, M69, or M69X) 
was effective when the fuel charge was more 
than 6 ft from the eaves. In a closed furnished 
bedroom, the M50 started slowly destructive 
fires. 

Miscellcmeous Tests m Attic and Snb-attic 
Structures.-'^ An extensive series of tests was 
conducted to study the effect of fuel consistency, 
fuel distribution, burning rate of fuel, effect of 
ventilation and design of structure, on the initi¬ 
ation and propagation of fire. These tests were 
conducted with the M69 bomb, and employed a 
Rhineland type attic and a furnished bedroom 
representative of German practice. 

The results of the investigation may be sum¬ 
marized as follows. 

1. Ample ventilation must be provided in 
order for incendiary bombs to be effective in 
establishing destructive fires. 


2. Napalm fuel having a consistency of 400 
to 600 g Gardner, appears to give optimum 
breakup and optimum burning rate in furnished 
bedrooms, being superior to the 9 per cent Na¬ 
palm gels and IM gels used in M69 production. 

3. In attics, fuel consistency is not so criti¬ 
cal, but again the 400 to 600 g consistency ap¬ 
pears best. 

4. The burning rates of thickened gasoline 
fuels depend on the surface exposed to the air. 
For equal surface areas the IM2, IMS, and 
Napalm fuels containing from 2 to 9 per cent 
thickener burned at the same rate as gasoline. 

5. The surface area of the fuel exposed after 
ejection depends on the consistency of the fuel, 
the force of ejection, and impact against a tar¬ 
get. These factors must be kept in mind in 
formulating the fuel for a particular bomb. 



Figure 19. Views of Factory Mutual incendiary- 
test room (upper) from the door and (lower) 
from the window. 


6. In furnished rooms, considerable breakup 
of fuel, with simultaneous ignition of several 
incendiary centers and a rapid build-up of tem¬ 
perature, appears desirable. 

7. From a consideration of the geometry of 


^ir F fP B N TIAM 





TESTS IN FULL-SCALE ROOMS AND BUILDINGS 



Figure 20. Layout and location of test points in Factory Mutual room. 



























































































74 


TESTING AND EVALUATION OF INCENDIARIES 


the furnished bedroom, combined with all the 
test data, it was estimated that 20 per cent of 
all M69 bombs ejecting within the room would 



Figure 21. Areas in Factory Mutual room vulner¬ 
able to E19 bomb. 


cause destructive fires if they contained gel of 
the optimum consistency. 

Tests by Factory Mutual Research 
Corporation^'’" 

Comparative evaluations of small incendiary 
bombs were made under controlled conditions 
in a furnished bedroom. The bombs were com¬ 
pared by determining the relative areas in 
which fires were started and went out of control 
by a stirrup pump after a waiting period of 
6 min. 


Description of Test Room. The test room 
measured approximately 12 ft by 15 ft, with a 
ceiling height of 7V2 ft. Figures 19 and 20 show 
the layout of the room. The walls and ceiling 
were covered with gypsum board for easy re¬ 
placement. The average weight of the furnish¬ 
ings was 3.2 lb per sq ft of floor area. 

Test Procedure. The bombs were placed in 
locations shown in Figure 20, and fired stati¬ 
cally. After 6 min elapsed, an experienced fire 
fighter and helper attacked the fire with a stir¬ 
rup pump, approaching through the adjoining 
room, where he encountered heat and smoke 
from the bedroom. If he was unsuccessful in 
dealing with the fire it was judged out of con¬ 
trol. 

Residts. The tests indicated that the E19 in¬ 
cendiary bomb would cause uncontrollable fires 
when burning within areas that amounted to 
67 per cent of the floor area. In Figure 21 the 
crosshatching shows the vulnerable area for the 
E19 bomb. The M50 4-lb magnesium bomb 
was found to be effective in only 7.2 per cent 
of the total area in similar tests. It was found 
that the temperature reached within the room 



0 I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 


TIME IN MINUTES 

Figure 22. Typical time-temperature curves for 
incendiary test in Factory Mutual room. Three 
thermocouples were at ceiling in locations shown 
in Figure 20. 

at the end of the 6-min waiting period was not 
a reliable index of the outcome of the test. In 
one test a temperature of 320 F at 6 min was 
recorded for a fire that could not be controlled. 

















































































TESTS IN FULL-SCALE ROOMS AND BUILDINGS 


75 


whereas in another test a temperature of 620 F 
was reached in 6 min, but the fire was put out. 
These observations have been confirmed by 
later work which has shown that when fur¬ 
nished rooms attain a maximum intensity of 
burning the temperature may reach 1800 F. 
Figure 22 shows typical time-temperature 
curves during an incendiary test. 

Tests at Diigway Proving 
Ground"^ ■' 

Although much valuable information regard¬ 
ing the penetration, proper functioning and 
incendiary effectiveness of small bombs had 
been obtained from mortar tests, it was recog¬ 
nized that airborne tests on full-scale target 
structures would be required in order to obtain 
a complete quantitative evaluation of the bombs. 
Such factors as the flight characteristics of the 
cluster, the functioning of the cluster fuze, the 
dispersion pattern of the individual bombs 
when released from a cluster, and the per¬ 
formance and functioning of the bombs could be 
evaluated by airborne tests without having an 
incendiary target, but it was felt that there 
might be factors the existence and importance 
of which would be revealed in full-scale air¬ 
borne incendiary tests. Such an appraisal 
seemed necessary in order to be sure that the 
bombs would be effective when released upon 
enemy targets. A location suitable for these 
tests was found at Dugway Proving Ground of 
Chemical Warfare Service, situated some 70 
miles southwest of Salt Lake City, Utah. Fig¬ 
ure 23 shows some views of this project. 

Description of Target StrucUires. 1. Ger¬ 
man structures. Six adjoining houses were 
built, three of the Rhineland type and three of 
the Central German type, similar to the Stand¬ 
ard Oil Development Company structures, but 
much larger. Three had roofs of slate on sheath¬ 
ing, and three had tile on battens. The second- 
story rooms contained heavy furnishings char¬ 
acteristic of German custom. 

2. Japanese structures. The Japanese dwell¬ 
ings were faithful reproductions of row houses 
occupied by factory workers. They were 
equipped with authentic straw floor mats and 
simulated furniture in an amount usually 


found in such dwellings. No trouble or expense 
was spared in making all details of these dwell¬ 
ings correspond with authentic Japanese prac¬ 
tice. 

Description of Tests. An elaborate program 
of tests included dropping the M50 and M52 
magnesium bombs, the M54 therm-8 bomb, and 
the M69 6-lb oil bomb. Both live and inert 
bombs were released at altitudes of 3,500 ft 
and 10,000 ft, from quick-opening clusters. Ex¬ 
tensive data were taken on every point of func¬ 
tioning and performance, in order to have a 
sound basis for establishing the relative merits 
of the bombs. When hits on the targets were 
obtained, a complete record of each bomb was 
made, including the point of entry, the path of 
the bomb through the structure until it came 
to rest, the location where the functioning and 
incendiary action occurred, and the incendiary 
result achieved. Fires were classified according 
to the time it took for them to reach various 
stages. Thus, the classifications Al, A2, and A3 
were assigned to fires which were judged to be 
going out of control by stirrup pumps within 
2, 4, and 6 min, respectively. Fires that did not 
develop rapidly, but which would eventually go 
out of control, were classified as B fires. Small 
fires which would go out even if unattended 
were called C fires. Dud bombs were designated 
D. In order to avoid excessive damage, the fires 
were attacked with garden hose or full-scale 
fire-fighting equipment as soon as the expert 
evaluators had established the classification of 
the fire. Data were likewise taken on fires 
caused by gel ejected by M69 bombs onto build¬ 
ings (ejection hits). Figure 24 shows a typical 
destruction fire in progress in a Japanese struc¬ 
ture. 

Results. Early in the program the M54 therm- 
8 bomb proved to be such a poor incendiary 
that it was given no further consideration. The 
M50 bomb was found to have excessive penetra¬ 
tion for the Japanese structures. In the German 
dwellings it penetrated to the attic or to the 
floor below, but caused no rapid fires, being 
effective only when it burned in a favorable 
location. The M52 magnesium bomb exhibited 
marked instability of flight, but showed that its 
penetrating characteristics and incendiary 
effectiveness were adequate for Japanese con- 



76 


TESTING AND EVALUATION OF INCENDIARIES 





Figure 23. Views of Du^-ay incendiary-test “Village.*' 


struction. The ^169 bomb was the most effective 
of the bombs tested, and showed itself to be a 
potent weapon against Japanese construction. It 
also caused some good fires in the German 
buildings, and it was adjudged the best of the 


bombs tested on these structures. Table o sum¬ 
marizes very briefly the results of these incen¬ 
diary tests; for more detailed data the reader 
is referred to the official ivport. 

Fire-Fighting Teifta: icith the Mt>9, Because of 


ItTruaKITOAl? 










TESTS IN FULL-SCALE ROOMS AND BUILDINGS 


77 


the belief that the Japanese are resourceful and 
determined fire fighters, it was decided to con¬ 
duct a series of tests in which the fires would 
be attacked soon after the bomb had functioned. 
M69 bombs were placed so as to eject gel into 
predetermined locations, selected on the basis 
of earlier airborne tests. The bomb was fired 
electrically, and immediately thereafter a man 
equipped with stirrup pump or sand and shovel 
was permitted to enter the building, search for 
the fire and endeavor to put it out. An assistant 
was available to operate the pump. Tests were 
also made in which two bombs were fired simul¬ 
taneously. The fire fighter and his assistant then 
attacked the most readily accessible fire until it 


upward to allow for the defensive measures 
that would probably be taken by the enemy. 

These tests led to the following conclusions. 

1. Attack within 1 min would reduce poten¬ 
tial fires per 100 AN-M69 bombs dropped from 
46 to 10.5 as a minimum. 

2. Previous estimates of 6 to 10 tons per sq 
mile were too low. Based on 50 per cent roof 
area, of which 50 per cent are multistoned 
structures, the bomb density should be about 
40 tons per sq mile for reliable destruction. 

In comparison with bomb densities used in 
the last six months of World War II, the above 
figure is quite low. However, it should be 
pointed out that the densities actually used may 


Table 3. Results of incendiary bomb tests on Dugway structures.* 


Fire 

classification 

AN-M50 

Japanese houses 
AX-M52 

AX-M69 

AX-M50 

German houses 
AX-M52 

AX-M69 

A 

22% 

26% 

68% 

0% 

0% 

37% 

B 

20% 

IWo 

13% 

26% 

18% 

16% 

C 

58% 

60% 

19% 

71% 

82% 

-17% 


*Dud bombs are excluded from the summary of bomb tests in this table. 


was extinguished, and then proceeded to locate 
and attack the second fire. Both experienced 
and inexperienced personnel were used during 
the course of the tests. 

Results. Of 36 bombs attacked by both ex¬ 
perienced and inexperienced fire fighters using 
simple fire-fighting methods, 7 caused fires that 
went out of control. Of the single fires in readily 
accessible locations, 5 out of 37 went out of 
control; in locations difficult of access, 3 out of 
6 went out of control. When two bombs were 
fired simultaneously and each caused an A or B 
fire, 8 out of 16 went out of control, despite at¬ 
tack by fire fighters. The general conclusion was 
reached that fires initiated by the AN-M69 
bomb in Japanese houses could frequently be 
controlled by fire fighters, and that the impor¬ 
tant factors in such control were the method 
utilized, the experience of the individual, the 
accessibility of the fire, and, above all else, the 
time that elapsed before the fire was attacked. 
The results of these tests indicated that pre¬ 
vious estimates of the effectiveness of the M69 
for the bombing of Japan would need revision 


have been unnecessarily high, and that there 
probably was a big difference between density 
dropped and density on the target area. 

Incendiary Tests in Experimental 
Japanese Room"® 

The tests at Dugway had shown that small 
incendiary bombs, particularly the AN-M69 
and the M74, were effective in starting fires in 
Japanese dwellings, and that these dwellings 
were vulnerable to incendiary attack and easily 
destroyed by fire. Tests in England with the 
AN-M69 and other small incendiary bombs had 
indicated that small bombs were inadequate, 
seldom starting fires that would go out of con¬ 
trol in a reasonable time, and then only when 
the bombs functioned in a few favorable loca¬ 
tions. It was pointed out that the moisture con¬ 
tent of the wood in the Dugway targets had 
averaged only 11 per cent in the first series of 
tests, and had been still drier in some later 
tests, moisture contents in the range of 3 to 6 
per cent having been recorded for the hung 















78 


TESTING AND EVALUATION OF INCENDIARIES 



50 MINUTES 


ceilings. Serious doubt was expressed as to the 
validity of the conclusions drawn from the 
Dugway tests, in view of claims that the mois¬ 
ture content of wood in Japan might approach 
20 per cent. The British urged that larger 
bombs, such as the jet bombs, J-30 and J-20, 
were needed for effective attack on Japan. The 
implications were so serious that a British mis¬ 
sion visited the United States in November 
1944, and held several discussions in an at¬ 
tempt to reconcile the differences that had been 
found in the results of tests in America and 
England. 

It was finally agreed that tests would be 
conducted by both groups, employing an ex¬ 
perimental Japanese room designed to embody 
essential elements of construction, and assem¬ 
bled entirely from panels preconditioned to a 
proper moisture content. 

Descriptiori of Test Room. Figures 25 and 26 



Figure 2.5. Interior of experimental Japanese 
room at Edgewood Arsenal. 



70 MINUTES 


Figure 24. Destructive tire in progress in a Japa¬ 
nese structure at 12, 30, 50, and 70 min after im¬ 
pact. 


show the interior and exterior of the unit built 
at Edgewood Arsenal. The design was agreed 
upon in conference with British experts, and 
represented a compromise between American 
and British test structures. The test room 
proper measured 9 by 12 ft and was supported 
by a massive external framework. At one end 
was a noncombustible enclosure to simulate a 
plastered hallway. This was furnished with 
combustible ceiling panels, which would nor¬ 
mally be present above a hallway. The test 
room was assembled immediately before each 
test, panels being removed from the condition- 


















TESTS IN FULL-SCALE ROOMS AND BUILDINGS 


79 



Figure 26. Exterior of experimental Japanese 
room, with fire in progress. 

ing room and set in position in 15 to 20 min. 

Since no reliable data were available on the 
moisture content of wood in Japan, it was de¬ 
cided to conduct wood-moisture equilibrium 
studies at a location where the climate corre¬ 
sponded closely to the summer climate of the 
Tokyo district. Key West, Florida, was a suit¬ 
able place during the winter months, and sam¬ 
ples of wood were there exposed out of doors 
and in several rooms in three different houses. 
Weights of samples, and determinations of rela¬ 
tive humidity and temperature of air, were 
taken twice a day over a period of several 
weeks. It was concluded that a maximum wood- 
moisture content of 15 per cent was to be ex¬ 
pected in houses in the Tokyo district. The 
panels for the experimental Japanese room 
were therefore conditioned to a moisture con¬ 
tent in the range of 15 to 17 per cent. 

Test Procedure. The AN-M69 bomb was 
chosen for the tests, because it was in large- 
scale production and scheduled for early use on 
Japan. The periphery of the room was divided 
into zones within which the combustibility was 
considered uniform. On the assumption that the 
angle subtended by a zone at the center of the 
room was a fair average of the angles sub¬ 
tended from points uniformly distributed over 
the floor, angles from the center to each zone 
were measured to determine the probability of 
ejection into that zone (see Figure 27). By 


combining these probabilities with results of 
incendiary tests on each zone, the fraction of 
the total ejection shots by AN-M69 bombs found 
to be effective was established at 77 per cent. 
Allowing for a decrease of one-half in effective¬ 
ness due to penetration of gel through the 
shutters to the exterior, one concludes that 38 
per cent of the bombs penetrating into the room 
would yield fires that would become uncon¬ 
trollable within 5 min. This last may be an 
overcorrection. A few M74 bombs were fired 
into the room from the vertical mortar, and the 
results indicated a degree of effectiveness simi¬ 
lar to that obtained from the AN-M69. 

Conclusions. From the results of these tests 
it was concluded that (1) Japanese domestic 
construction of the type occupied by factory 
workers, and conditioned to a moisture content 
of 15 to 17 per cent, is easily ignited and vul- 


B 6 C 



Figure 27. Layout and vulnerable zones in an 
experimental Japanese room. 

nerable to fire; (2) the AN-M69 bomb is ade¬ 
quate for the purpose; and (3) the M74 bomb 
is also adequate for the purpose. 

Before these results were published, the his- 


















































80 


TESTING AND EVALUATION OF INCENDIARIES 



Figure 28. View of an Eglin Field factory-type, incendiary test building. 


toric raids of March 1945 on Tokyo with the 
M69 bomb had amply demonstrated the overall 
effectiveness of that bomb, particularly when 
dropped in such numbers as to overwhelm de¬ 
fensive measures which might have coped with 
smaller numbers of bombs. All tests revealed 
that small incendiary bombs are easily con¬ 
trolled in the early stage of their burning 
against a target, and that the indispensable 
condition for their success in starting fires is 
that they be undisturbed for periods of time up 
to 5 or 6 min. 


Tests at Eglin Field 

Because the policy of the American Air 
Forces in 1943 and 1944 was to concentrate on 
the precision bombing of industrial targets, a 
need was felt to evaluate incendiary bombs by 
airborne tests employing a full-scale factory 
structure. The only available structure was one 
situated on H field at Edgewood Arsenal, Mary¬ 
land, and the heavy demands on its use by 
CWS and by Ordnance, combined with the fre¬ 
quent occurrence of weather that prevented 
bombing from high altitude, made it advisable 
to erect a new building in a more favorable lo¬ 
cation. Permission was obtained by NDRC to 
construct a target building at the AAF Prov¬ 
ing Ground at Eglin Field, Florida. Here were 
available all types of airplanes, all necessary in¬ 
struments, and a skilled personnel to operate 


them. Ground was broken for this structure in 
November 1943, and it was ready for use in 
March 1944. 

Description of Target Structure. A major 
consideration in designing the building was to 
include those types of roof construction which 
would be representative of the roofs commonly 
found on enemy factories. The building would 
then not only serve for testing the penetration 
and functioning of all incendiary bombs being 
developed, but would yield data directly appli¬ 
cable to the planning of incendiary raids on 
enemy targets. 

A side elevation of the target structure is 
shown in Figure 28. The structure was of steel- 
frame construction, with a concrete floor, ex¬ 
cept for one section measuring 140 by 68 ft 
which had wood-block flooring covered with 
tar. The width of the building was 140 ft, and 
the total length was 375 ft. There were three 
sections, the lengths of which were 100 ft, 125 
ft, and 150 ft, respectively. The first section was 
three stories high, of reinforced concrete. The 
floors of intermediate stories were 8-in. rein¬ 
forced concrete and the roof was 6-in. rein¬ 
forced concrete. The second and third sections 
were laid out in bays measuring 25 by 20 ft, 
with a height of 20 ft between the floor and 
roof. In the second section, half the roof was 
made up of 2 to 5 in. of cinder concrete over 
3-in. hollow tile, covered finally by two layers 
of asphalt felt. The other half was 3 in. of cinder 
concrete over 3V1> in. of light concrete, covered 









TESTS IN FULL-SCALE ROOMS AND BUILDINGS 


81 


by two layers of asphalt felt. The third section 
had a sawtooth roof consisting of light steel 
framing which supported glazed windows and 
1-in. wooden sheathing covered with two layers 
of asphalt felt. The sides of the building were 
open and there was a concrete apron 50 ft wide 
surrounding the entire structure. Two hundred 
yards away was a bombproof shelter from 
which observers could view the length of the 
target building. 

Use of the Eglin Field Structure. The prin¬ 
cipal data obtained in hits on the building were 
on penetration through the various types of 
roof and on the functioning of the bomb after 
penetration and subsequent impact on the floor. 
The AN-M69 bomb was tested on several occa¬ 
sions, being released in aimable clusters at alti¬ 
tudes up to 30,000 ft, with the cluster fuze set 
to open the cluster at any desired height above 
the target. It was found that a free fall of the 
individual AN-M69 bomb of approximately 
5,000 ft was necessary to permit the bomb to 
decelerate to its normal terminal velocity of 
about 225 ft per sec. 

The AN-M69 penetrated the sawtooth roof, 
and also the various light-weight roof slabs 
when no reinforcing members or supporting 
beams were encountered. It failed to penetrate 
the 6-in. reinforced concrete roof. 

By an analysis of data on the prevalence of 
various roof types in Germany, and by com¬ 
parison with previous test data, it was con¬ 
cluded that the common incendiary bombs 
would penetrate the following percentages of 
German industrial roof area: M50, 81 per cent; 
M47, 87 per cent; M69, 74 per cent; M69X, 
75 per cent. 

Subsequent photocover indicated that the 
AN-M69 and M69X would penetrate the roofs 
on over 90 per cent of the high-priority indus¬ 
trial targets in Japan. 

In cooperation with Chemical Warfare Serv¬ 
ice, NDRC conducted a series of tests with the 
M47A2 70-lb oil bomb, to determine whether 
the M12 burster, black powder and magnesium, 
or the M13 burster, tetryl and white phos¬ 
phorus, should be preferred for this munition. 
The M12 burster is slower in its action and 
does not bring down as much roof material as 
the M13 when the bomb penetrates cinder con¬ 


crete or tile roof slabs. The faster action of 
the M13 burster appears to cause more gel to 
lodge against sawtooth roofs, frequently caus¬ 
ing roof fires. The general conclusion was 
reached that either burster gave satisfactory 
ignition of gel and that neither appeared to 
have any marked superiority over the other. 

In the tests at Eglin Field no attempt was 
made to evaluate the incendiary effectiveness 
of the bombs. Circumstances were noted under 
which roof fires occurred, and in some tests 
rough wooden benches were placed about the 
floor. 

As in other airborne tests, observations were 
made as to the ballistics and functioning of the 
cluster, the flight characteristics of the indi¬ 
vidual bombs, and the dispersion pattern 
around the center of impact. Recovery of bombs 
was frequently made, and causes of malfunc¬ 
tioning determined. The overall results of these 
tests contributed much valuable information 
that could be gotten in no other way, and pro¬ 
vided a sound basis for predicting the results 
that might be expected from bombs dropped 
in actual attacks. 


Tests at Edgewood Arsenal’''’ 

The industrial target structure at Eglin Field 
proved to be so useful that the Chemical War¬ 
fare Service erected a similar structure at 
Edgewood Arsenal in the fall of 1944. 

Minor changes over the Eglin Field structure 
were made, such as omitting the tar-covered 
wooden block flooring, and the substitution of 
metal or laminated plastic for most of the glass 
panes in the sawtooth section. An important 
change was the addition of hinged metal panels 
which enclosed the structure on all sides and 
minimized the effect of wind while still permit¬ 
ting adequate ventilation. The Incendiary Eval¬ 
uation Project provided wooden benches, stacks 
of packing cases, storage bins, radial targets, 
and cardboard cartons, which were arranged 
in the two sections having light roofs. These 
covered approximately 5 per cent of the floor 
area, and permitted an evaluation of the incen¬ 
diary effectiveness of the bombs. This particu¬ 
lar floor loading was selected for tests with the 


jnryWkTiiPjaTJAr: 





82 


TESTING AND EVALUATION OE INCENDIARIES 


M47 bomb, which distributed gel over an area 
of about 3,000 sq ft, and provided a good 
chance that several different targets would re¬ 
ceive gel when an M47 hit into the building. 

In tests on this building with the M74 8-lb 
incendiary bomb, the angle of descent of the PT 
gel was determined by noting the hole in the 
roof and the position on the floor where the gel 
had struck. In 25 hits on the sawtooth section 
the angle between the vertical and the path 
followed by the gel varied from zero to 60 de¬ 
grees, the average being 26 degrees. This im¬ 
portant fact was combined with other data 
obtained in mortar tests to establish the proba¬ 
bility of an M74 starting a fire in a factory setup 
which contained combustible targets covering 
25 per cent of the floor area. (See Section 3.3.) 

In tests with the AN-M50A2, it was found 
that a high percentage of bombs that pene¬ 
trated the sawtooth roof failed to function 
upon reaching the floor. This was apparently 
caused by the failure of the fuze to be activated 
by the slight deceleration that accompanied 
penetration through such a light roof, which, 
however, rendered the fuze insensitive to the 
subsequent shock upon hitting the floor. These 
results indicated the need for a more sensitive 
fuze than the one that had been incorporated 
to meet safety requirements in handling the 
bomb, in order to insure a satisfactorily high 
percentage functioning on light roofs. 

Tests were also run with the AN-M69, the 
E19, and several 500-lb incendiary bombs being 
developed by CWS. 

An evaluation was also made of incendiary 
fillings for the 4.2-in. mortar shell, which was 
fired into the building containing the incendiary 
targets. 


3- FUNDAMENTAL STUDIES ON THE 
IGNITION OF WOOD 

Most of the combustible material used in 
building construction and furnishing is wood, 
and a knowledge of the factors which govern 
the burning of wood is fundamental to the de¬ 
velopment of a sound technique of incendiary 
bomb testing. 

When wood is heated the first result is that 


some of the moisture it contains is vaporized 
and driven off. Decomposition of the wood sub¬ 
stance also begins to take place with the 
evolution of heat, and the volatile products of 
this decomposition are also driven off. If the 
source of heat is large enough to raise the tem¬ 
perature of the wood continuously, a point is 
reached at which this endothermic decomposi¬ 
tion proceeds with almost explosive violence if 
a pilot flame is applied. At higher temperatures 
ignition takes place spontaneously. The con¬ 
tinuance of this burning, once it has been 
started at the surface, can only take place if 
the heat liberated at the surface, plus the heat 
from the initial source, are together sufficient 
to drive off the interior moisture, raise the 
temperature of successive layers of wood to the 
ignition point, and supply heat loss out through 
the wood to its unheated face. These various 
factors are considered in more detail under 
the following headings. 


Radiation Density Required for Ignition 

This factor in the problem was studied by ex¬ 
posing woodblocks of various species of wood 
to heat from a standard radiating source and 
measuring the time necessary for ignition. At 
average moisture contents it was found that a 
minimum value of about 18,000 Btu/hr/sq ft 
was necessary for self-ignition. At an intensity 
of 20,000 Btu/hr/sq ft ignition occurred in 25 
sec; at 50,000, in 3 sec. These results correspond 
to total inputs of 125 and 40 Btu/sq ft, respec¬ 
tively, illustrating the decrease in total energy 
required as the rate of input increases. When 
a gas pilot flame is applied, instead of relying 
on spontaneous ignition, the intensity of irradi¬ 
ation required drops markedly, 12,000 Btu/sq ft 
per hr for ignition in 25 sec compared to 20,000 
without a pilot flame. Although initiation of 
fire is accomplished with a minimum of total 
energy if its intensity is a maximum, per¬ 
sistence of the flame is very brief after removal 
of the heat source, because of the substantial 
absence of any stored heat in the wood layer 
behind the flame. A sustained intensity of ir¬ 
radiation of about 10,000 Btu/sq ft per hr was 
found necessary to maintain the flame on a 



FUNDAMENTAL STUDIES ON THE IGNITION OF WOOD 


83 


wood surface indefinitely, or until an edge or 
supporting member was involved. 

Little difference in inflammability was found 
for a number of wood species tested. 


3.C.2 Effect of Moisture Coiitent^^ 

In the tests just referred to blocks of different 
moisture content were used, but there was little 
effect on the time required for either pilot- 
ignition or self-ignition under the conditions of 
high irradiation density used, since only the 
surface of the wood was then involved. When, 
however, the continuance of burning was at 
stake, moisture content was found to have a 
material effect. 

In another series of tests, sticks of Douglas 
fir 1x2x714 in. of different moisture contents 
were located in such a way with respect to the 
burning fuel used as a heat source that the 
transference of heat was effected more by con¬ 
vection and conduction than by radiation. The 
samples were exposed to various input rates 
and the ignition times measured as well as the 
weight loss after 1 min burning. A marked 
difference in the behavior of 8 and 15 per cent 
wood moisture was found. Depending on the 
rate of heat input, the ignition time of the drier 
wood was from 43 to 58 per cent of that for 
the wetter wood when using a pilot flame, and 
from 60 to 80 per cent without a pilot. With 
pairs of samples spaced 1/2 in. apart and the 
2x7-in. surface facing, those containing 8 per 
cent moisture continued to burn 3.7 times as 
long as the samples having 15 per cent moisture 
when the heat source was removed immediately 
after ignition. 

This effect was strikingly demonstrated by 
using pairs of vertical planks spaced 2 in. apart, 
with a known amount of incendiary material 
burning between them at the base. In one test 
using 0.6 lb gasoline soaked in 0.1 lb cellucotton 
as the fuel, it was found that with 11 to 12 per 
cent wood moisture, flames reached the top of 
the planks (12 ft) after 3 min and the structure 
continued to burn to destruction, whereas, with 
21 to 22 per cent wood moisture the flames took 
5 min to reach 7 ft, after which they receded 
and the fire died out. 


In all subsequent tests, therefore, the wood 
used was preconditioned to a known moisture 
content, and special rooms were built for this 
purpose for the Incendiary Evaluation Project 
at Edgewood Arsenal. 

The actual value of moisture content to use 
for any set of tests involved a knowledge of (1) 
the relation between the relative humidity of 
the atmosphere and the equilibrium moisture 
content, and (2) the average relative humidity 
in the locality selected for incendiary bombing. 

The generally accepted equilibrium relation 
between relative humidity and wood moisture 
content was found to be only approximately 
true. Since this relation was established as a 
result of tests carried out on wood shavings 
with a high specific surface, tests were there¬ 
fore made in which wood slabs of different 
thicknesses were exposed to atmospheres of 
controlled temperature and relative humidity, 
and allowed to approach their equilibrium mois¬ 
ture content first from above and then from 
below."^*^ The direction of approach, the species 
of the wood, and its previous heat treatment 
were all found to have a marked effect on the 
final moisture content established. Especially 
was this so in the case of Douglas fir, which is 
frequently kiln-dried at a higher temperature 
than other woods, a process which appears to 
lower its equilibrium moisture content by as 
much as 2 to 4 per cent. 

Studies were made of existing climatic data 
for Germany and Japan, and estimates made 
of the probable effect of building construction 
and living conditions on the inside relative 
humidity in relation to the outside relative 
humidity, which is normally recorded by the 
Weather Bureaus. 

For Germany it was predicted that the values 
for wood moisture content would be as follows: 

Attic Living quarters 

Summer Winter Summer Winter 

8-12 12-15 11-13 10-12 

Information from German sources indicated 
that it would be more accurate to work at the 
higher ends of these ranges. 

In the case of Japan, a detailed study was 
made in houses in Key West, Florida, where 
climatic conditions in winter are generally sim- 



84 


TESTING AND EVALUATION OE INCENDIARIES 


ilar to those of Tokyo in the summer, and where 
living conditions and occupational densities 
could be found which were comparable with 
those known to exist in Japan.^*^ As a result of 
this study, it was established that the most 
likely value for the moisture content of interior 
wood in Japan in the summer (the dampest 
period) was 15 per cent, a value which was 
used in all subsequent tests.^*^ 


3.5.3 Effect of Wood Thickness 

In early experiments it was found that iso¬ 
lated wood panels over a certain thickness, 
about 1/4-V2 would not continue to burn 
after the igniting source had been removed. For 
example, two vertical planks spaced 2 in. apart, 
one in. and the other % in- thick, were 
ignited on their inside faces with burning in¬ 
cendiary fuel at the base and allowed to burn 
until both surfaces were burning vigorously. 
The panels were then separated, and while the 
i/4-in. plank continued to burn to destruction, 
the fire on the %-in. plank died out. Measure¬ 
ments showed that only a small proportion of 
the heat produced at the burning surface was 
transmitted inwards, and in the case of the 
thick wood was conducted away from the sur¬ 
face too rapidly for the temperature of the 
next adjacent layer to reach the ignition point 
and thus allow burning to continue. Much of 
this heat lost from the surface could be saved, 
and the general level of temperature raised 
considerably, by placing the incendiary fuel in 
such a way that two or more adjacent surfaces 
were ignited simultaneously and could estab¬ 
lish mutual interchange of heat. For example, 
it was shown that a 4-lb magnesium bomb burn¬ 
ing on the floor outside, but close to an open- 
topped box made of 1 in. thick wood, did not 
start a continuing Are. When, however, the 
bomb was placed inside the box where mutual 
support was provided by all the interior faces, 
a rapidly destructive fire resulted. 

In many instances (light paneled European 
furniture, Japanese screens, shutters, etc.) it 
was found that the wood could be fired directly, 
provided the burning time of the incendiary 
fuel was longer than the minimum necessary to 


ignite the surface. In other instances when the 
objects were heavy constructional members of 
German attics, heavy furniture and industrial 
furnishings, etc., it was found necessary to 
locate the fuel so that more than one surface 
could be ignited at a time. An interesting case 
in point was the adoption of the horizontal gel 
ejection principle in the AN-M69 bomb, which 
enables the gel, in a German attic, for example, 
to be thrown right into the eaves where the 
fires on the floor and the sloping boarded roof 
can reinforce one another and grow. 


3 . 3 . t Effect of Wood Species^' 

The existing literature on the relation be¬ 
tween the burning properties of wood and 
species was found to be somewhat conflicting, 
although there was general agreement on the 
fact that the higher the density of the wood the 
more difficult it was to ignite. The problem be¬ 
came acute when it was necessary to select an 
American wood that would be a satisfactory 
substitute for the mahogany and oak furniture 
which was stated to be prevalent in Germany. 
Two kinds of test samples were used: sticks 
1x1x18 in. and boards 1x6x18 in. In both cases 
the ignition source was allowed to impinge at 
an angle on to the sample. As a result of a large 
number of tests, it was found that the average 
ignition time varied from 46 to 162 sec for the 
following species of wood in order: Eastern 
spruce, Mexican mahogany, white oak, Philip¬ 
pine mahogany, Douglas fir, rock maple, and 
West Virginia maple. From this it was con¬ 
cluded that standard American maple furniture 
would be as difficult to ignite as the wood of 
typical furniture in Germany. 

For Japan the problem was different, since 
the Japanese house contains practically no fur¬ 
niture and reliance must be placed on ignition 
of the light wooden screens and shutters which 
take up most of the periphery of the room. 
The woods most frequently used for this pur¬ 
pose in Japan are hinoki and sugi, and experts 
advised that the closest available substitute for 
these woods from the point of view of density 
and essential oil content was Sitka spruce. In 
tests at Dugway a good deal of pine had been 



ANALYSIS OF ATTACKS ON ENEMY TARGETS 


85 


used, and in England, Japanese type houses had 
been built of Douglas fir. It was therefore de¬ 
sirable to carry out a direct comparison of 
these three species under conditions simulating 
the burning of thin vertical surfaces. Vertical 
panels, 5 ft square, made of carefully selected 
V4 in. thick, butt-jointed boards of each species, 
were preconditioned to the same moisture con¬ 
tent and then ignited by burning a given 
amount of incendiary fuel at the base of one 
side. The progress of the burning was noted, 
and when the fires had died out the unburnt 
material was weighed. The results are shown 
in Table 4 and Figure 29. From these results 
it was concluded that these three species show 
appreciable differences in their burning charac¬ 
teristics, corresponding roughly with their dif¬ 
ferences in density. 


Table 4. Comparative burning characteristics of 
wood. 



Douglas 

fir 

Sitka 

spruce 

Ponderosa 

pine 

Density of wood 
Time of maximum 

0.57 

in- 

0.44 

0.33 

tensity of fire 
Time of marked 

4'30" 

di- 

4'0" 

3'20" 

minution of fire 

6' 

6' 

9' 

Proportion burned 

28% 

30% 

66% 


Confirmatory evidence of the difficulty of 
starting fires with Douglas fir was obtained 
during the series of tests with the Jap struc¬ 
tures at Edgewood. Sitka spruce was usually 
used, but on two occasions comparative tests 
were carried out with Douglas fir, and in both 
cases the fires were more sluggish. The par¬ 
ticularly high-density Douglas fir used in Eng¬ 
land was considered to be an important con¬ 
tributory factor in the difficulty of starting 
fires there. 


3 ^ ANALYSIS OF ATTACKS ON ENEMY 
TARGETS 

In the last analysis the evaluation of an in¬ 
cendiary is its effectiveness on enemy targets. 
Most of the analyses of air attacks on enemy 
targets were made by the Ministry of Home 
Security, RAF Air Intelligence, and U. S. AAF 
Air Intelligence, including the Joint Target 



PINE 


Figure 29. Comparative burning test of three 
wood species. 

































































86 


TESTING AND EVALUATION OF INCENDIARIES 


Group, but some analyses were made by NDRC 
groups. Below are summarized 2 of NDRC’s 
contributions in this field: One covering the 
analysis of attacks on German targets by the 
group established under Service Project AN-23, 
and one giving an analysis of incendiary attacks 
on Japanese cities by W. T. Knox of the Stand¬ 
ard Oil Development Co. 

^ Analysis of Air Attacks by NDRC 
AN-23 Group 

In August 1944, Divisions 2 and 11 and the 
Applied Mathematics Panel jointly accepted 
Service Project AN-23, the objectives of which 
were to gather data on the results of bomb at¬ 
tacks on European factory targets, analyze the 
results to establish the effectiveness of the vari¬ 
ous weapons used, and, if possible, evolve a 
technique of predicting the results of planned 
attacks, particularly on Japanese industry. 
Primary concern was the prediction of damage 
due to combined high-explosive and incendiary 
attack. The work of collecting data, described 
in detail in EWT-ld, was carried out in Europe. 
After elimination of all the American attacks 
on which data were incomplete or unsatisfac¬ 
tory, 38 remained. These yielded data on the 
physical character, before and after attack, of 
1,276 separate building units, together with the 
probable density of attack on them. In addition, 
complete data were collected on one RAF at¬ 
tack, involving damage to 14 different industrial 
plants. The data have proved adequate in quan¬ 
tity and quality for establishing many illumi¬ 
nating generalizations concerning bombing 
operations, and have yielded vulnerability equa¬ 
tions which should be useful in planning at¬ 
tacks. A summary of the results of the study 
appears below. 

In the spring of 1945 a program of control 
attacks for the 20th Air Force was prepared. 
This was adopted in the field; the results were 
sent to Washington and were analyzed with a 
view to improving the effectiveness of attacks 
against Japanese industry. 

Data Collection and Recording. For each of 
the attacks complete damage assessments were 
obtained from photo-interpretation carried out 
chiefly by DIDAS of the 8th Air Force and the 


Interpretation Unit of RE8 at Princes Ris- 
borough. The following additional data were 
collected at their source: the number of bombs 
aimed at the target, their type, size and fuzing, 
the identification number of the attacking 
groups, the number of planes and shape of 
formation flown, intervalometer setting used, 
bombing altitude, heading, track, time of bomb 
release. The study of a number of attacks had 
to be abandoned because the data were found 
at the source to be confusing, incomplete, or 
occasionally contradictory. Bomb plots were 
made of the locations of HE bombs within the 
site rectangle, based on pre- and post-attack 
photocover, for all the attacks studied. 

To permit a quick and accurate examination 
of the data for indication of various suspected 
relationships among the variables, a punch-card 
system was adopted, with one card for each of 
the 1,276 building units (see EWT-1, 1). The 
punches on each card recorded the raid num¬ 
ber, the building number, per cent of the floor 
covered by combustible material, roof classifica¬ 
tion as to combustibility, per cent of floor area 
subject to fire, building plan area to nearest 
100 sq ft, number of floors, damage in hun¬ 
dreds of sq ft to structure and contents (sep¬ 
arated into HE, fire, and mixed damage), super¬ 
ficial and contents damage (separated into fire 
and mixed damage), internal damage (sep¬ 
arated into HE and fire), type of weapon used, 
approximate density of attack for each weapon 
(low, medium, or high). 

Preliminary Tests on Validity of Data. Ac¬ 
curate estimation of the number of hits on a 
target is obviously a first requirement for as¬ 
sessing the performance of the various weap¬ 
ons. Determination of HE hits on a site rec¬ 
tangle was by actual plotting of bomb craters. 
To check the identification of bomb hits from 
photocover, the number of total photo-identi¬ 
fied hits in a given target area was multiplied 
by the fractional built-up-ness of the target. 
The result was compared with the number of 
building hits identified. The agreement was 
from +6 per cent to —3 per cent (see EWT-le). 

Incendiary bomb density on a site rectangle 
was calculated by multiplying the actual density 
of HE bombs (determined as described above) 
by the ratio of incendiaries to HE bombs in the 





ANALYSIS OF ATTACKS ON ENEMY TARGETS 


87 


plane loads. In EWT-5a, this method was 
checked by comparison with a few known-to- 
be-incomplete M47 IB plots, and a method was 
developed for correcting these plots to a com¬ 
pleted basis for comparing densities in different 
parts of the target area. The results are in fair 
substantiation of the simpler procedure relied 
on exclusively in the weapon analysis studies. 

The accuracy of roof classification is im¬ 
portant in incendiary studies. Pre-attack photo¬ 
cover had been used at Princes Risborough to 
classify roofs. In EWT-lf this classification w'as 
compared with the better classification based 
on post-attack photocover. It was found that 
80 per cent of the roofs had been classified cor¬ 
rectly. Based on a classification of 1,233 roofs, 
68.5 per cent of building units had combustible 
roofs, and 60 per cent had both combustible 
roofs and combustible floors. 

A homogeneous target is one comprising 
building units in which all units are essentially 
equally responsive to attack by a particular 
bomb. A reasonable approximate vulnerability 
equation for such a target is F = 1 — ^ 

Let X = the fraction of the total density, 
d = (Z)i + Z)o) which is of type (2), i.e., 
X = D 2 /{Di 4 - Do). It is then easy to show 
that the gross MAE based on the total density 
varies from Mi when a; = 0 to Mo when x = 1, 
and is linear in x. This provides a test for homo¬ 
geneity of targets. When applied, the test indi¬ 
cates that noncombustible roof buildings are 
moderately homogeneous, but combustible ones 
are not (see EWT-lh). 

Building Types. Classification of buildings by 
roof type has already been mentioned above. 
The spans of the principal structural members, 
the number and spacing of columns, the height 
of the structure, presence of traveling-crane 
runways are all features significantly affecting 
the resistance of a building to HE damage. 
Based on a classification of 1,276 building units, 
the dominant types were found to be industrial, 
single-story buildings of less than 10,000 sq ft 
floor area (38.4 per cent), multistory framed 
and wall-bearing buildings (9.6 and 11.6 per 
cent), and large single-story buildings without 
traveling cranes, of simple beam-and-column or 
truss construction (11.1 and 15.4 per cent). 

Structural HE Damage. Based on 178 build¬ 


ing units, the mean area of effectiveness of the 
500-lb U. S. GP bomb was found to vary for 5 
building types from 2,600 to 3,300 sq ft per 
bomb hit including no-damage hits, or from 
3,100 to 4,100 sq ft excluding such hits. These 
are plan areas in multistory buildings. The floor 
damage is represented by the figures above, 
multiplied by the number of stories. For details 
see EWT-2f. 

The near-miss effects of the 500-lb GP bomb 
were studied in EWT-lj. Based on 433 analyz- 
able cases of misses within 45 ft of a building, 
it was concluded that a 500-lb GP bomb falling 
more than 15 ft from a European industrial 
building causes insignificant damage and that 
near-misses within 15 ft are but 10 per cent as 
effective as direct hits. 

Fh'e Spread. The determination of the impor¬ 
tance of fire spread in industrial buildings was 
essential to the development of a satisfactory 
quantitative relationship for predicting damage. 
Spread of fire damage was first studied in the 
case of pure HE attacks. Thirty-four analyz- 
able incidents were available in which no incen¬ 
diaries were used. It was found that HE fires 
starting in a single-story fire division with 
combustible roof usually spread through the 
fire division regardless of its size; in 10 to 14 
combustible-roof cases the fire completely 
burned out the fire division, and in 3 of the 
remaining 4 the fire was stopped by interior 
partitions (the average plan area per fire divi¬ 
sion was 20,000 sq ft). By contrast, in fire divi¬ 
sions with noncombustible or fire-resistant 
roofs, the average spread was 33 per cent; the 
average plan area of single-story fire divisions 
in this category was 100,000 sq ft. Spread to an 
adjoining fire division occurred whenever the 
HE bomb fell within 40 ft of a fire division (see 
EWT-2g). 

Mixed HE-IB attacks on single-story build¬ 
ings were studied next. An analysis of 148 fire 
divisions with combustible roofs and 28 with 
noncombustible roofs led to the conclusion that 
combustible roof fire divisions burn out com¬ 
pletely. Fire divisions with noncombustible 
roofs burn out completely if the plan area is up 
to 10,000 sq ft; for larger fire divisions, a limit¬ 
ing size of about 35,000 sq ft of burn-out is ap¬ 
proached. A quantitative expression of this 



88 


TESTING AND EVALUATION OF INCENDIARIES 


generalization is E = 35,000 (1 — e -^/sa.ooo). It 
shows that the area of damage E approaches 
a limit of 35,000 as A increases (see EWT-3c). 

If the buildings^ are multistory and the roofs 
and floors are combustible, a complete burn-out 
occurs due to fires from mixed attacks. If the 
roof is combustible and the floor noncombustible 
or resistive, 2- and 3-story buildings burn out 
about 1.5 floors (see EWT-3d). 

Sometimes several building units are grouped 
by target analysis into a single composite fire 
division. An analysis of 94 building units com¬ 
prising 36 composite fire divisions was made. 
Assuming that if a building unit in a composite 
fire division was not involved in a fire that de¬ 
stroyed the other buildings, then that building 
unit had been wrongly classified; it was found 
that at most 18 errors of assignment had been 
made on the 94 units. 

From the above studies it appears that the 
concept of a fire division is essential in the 
estimation of damage to be expected by incen¬ 
diary attack on industrial structures, and that 
knowledge of the areas of fire divisions in 
enemy targets is essential. 

The Probability of Starting a Serious Fire. 
The method of analyzing data to determine p, 
the probability of starting a serious fire, is pre¬ 
sented in EWT-3b for the 500-lb U. S. GP 
bomb, and in EWT-5b for incendiary bombs. 
These will be discussed separately. 

Py^obability of Fire Starting by HE. Based 
on 440 fire divisions in 14 targets attacked by 
HE bombs alone, their probability of starting 
a fire was estimated in several ways. The 
values center around 0.17, the extremes found 
in reasonable samples being 0.15 and 0.19. This 
probability of one-sixth is independent of roof 
construction and height, but probably depends 
on building type and combustibility of contents. 
The probability of a 15-ft near-miss causing a 
fire is 0.05 ± 0.05. 

From the above, it is concluded that when the 
area of a combustible-roof fire division is about 
6 times the high-explosive mean area of effec¬ 
tiveness of the bomb, the bomb damage by fire 
will equal its HE damage. Since the MAE for a 
500-lb HE bomb is around 3,000 sq ft, this calls 
for a fire-division area of around 18,000 sq ft 
to make the two effects equal. This is actually in 


the middle range of European industrial build¬ 
ings. It follows that fire damage by HE bombs 
is not a minor correction factor in calculating 
total damage, but is rather of about the same 
magnitude as the HE damage. 

Probability of Starting a Fire with an M^7 
IB (EWT-5c). Based on 560 fire divisions at¬ 
tacked with M47’s, of which 186 were damaged 
by fire, the p for the M47 was found to depend 
on height and estimated occupancy^ when the 
roof is combustible. A decrease of p with in¬ 
crease in height was observed in all but the 
highest occupancy class. Considering the facts 
that occupancy is an estimated quantity de¬ 
pending on available Intelligence and photo in¬ 
terpretation, and that true occupancy was for 
most cases unknown, deviations from a reason¬ 
able pattern of results are to be expected. It 
was concluded that p could be expressed'^ as the 
product of a roof-height factor, decreasing from 
unity for an 8-ft roof to 0 for a 55-ft roof, by 
an occupancy factor increasing from Vs for 5 
per cent occupancy to unity for 45 per cent 
occupancy. These functions are presented in 
Table 5. 


Table 5. Probability of starting a serious fire with 
an M47 bomb.* 


Height 

Height 

factor 

Occupancy 
per cent 

Occupancy 

factor 

8 

1.0 

5 

0.33 . 

15 

1.0 

15 

0.66 

25 

0.5 

25 

0.78 

35 

0.2 

35 

0.89 

45 

0.1 

45 

1.00 

55 

0.0 




♦Combustible-roof, European industrial buildings. 


Table 6 presents a comparison of the ob¬ 
served and calculated number of fires found in 
each height-occupancy class. 

The agreement is seen to be good. For non¬ 
combustible and fire-resistant roofs no depend¬ 
ence of p on height was found, but p does 
depend somewhat on occupancy. The value of 
p is around 0.05-0.06, varying from 0 for 15 
per cent occupancy to 0.13 for 35 per cent 
occupancy. 

Because there is generally a relation between 

a Occupancy is numerically measured as the per cent 
of the fioor area covered with combustible material. 

b p = height factor X occupancy factor. 








ANALYSIS OF ATTACKS ON ENEMY TARGETS 


89 


Table 6. Comparison of observed and calculated number of fires in each height and occupancy class.* 


Occupancy (%) 

5 

15 

25 

35 

45 

Totals in 
height class 

Height, ft 

7 to 9 



5 4.0 

(22) 

2 2.0 
(7) 

0 0.6 
(2) 

7 6.6 

(31) 

10 to 19 


2 1.7 

(5) 

20 20.3 

(54) 

19 17.3 

(46) 

1 1.2 
(2) 

42 40.5 

(107) 

20 to 29 


2 1.6 
(3) 

6 7.7 

(19) 

6 4.1 

(10) 

2 2.1 

(6) 

16 15.5 

(38) 

30 to 39 


0 0.6 
(1) 

1 2.5 

(9) 

2 1.7 

(4) 


00 

40 to 49 

0 0.0 

(1) 

0 0.2 
(1) 

1 0.9 

O) 

0 0.5 

(2) 

\ 


1 1.6 
(8) 

50 to 59 


0 0.0 
(1) 

0 0.5 

(2) 

0 0.0 
(1) 


0 0.5 

(4). 

Totals in occupancy 
class 

0 0.0 

(IJ 

4 4.1 

(11) 

33 35.9 

(110) 

29 25.6 

(70) 

3 3.9 

(10) 

69 69.5 

(202) 


*Combustible-roof buildings, attack No. 10 excluded. 

Upper left entry is observed number of fires. 

Upper right entry is calculated number of fires. 

Lower entry in parentheses is number of fire divisions in sample. 

building type and roof height, one may expect 
p to vary with building type. This is borne out 
by the data. Small single-story buildings of less 
than 10,000 sq ft have a high p, near unity; 
when the area exceeds 10,000 ft but the span is 
less than 75 ft, p drops to 0.39; when the area 
exceeds 10,000 sq ft and the span exceeds 75 ft, 

p = 0.02. 

Probability of Starting a Serious Fire ivith 
an M50 IB (EWT-5d). The available data were 
not sufficient to establish p with the same cer¬ 
tainty as for the M47. 135 fire divisions, of 
which 51 were damaged, were analyzed. In addi¬ 
tion to the inadequacy of the data, there is 
some doubt as to the right to determine number 
of hits on a fire division from the average 
density over the site rectangle, because of the 
non-random fall of bombs released in clusters. 
However, the same general trends in p were 
noted as for the M47; namely, the distinct dif¬ 
ference between combustible and noncombus¬ 
tible roofs =: 0.05 and 0.01, respectively), 
and a strong effect of height and of occupancy. 
Smoothing the data leads to recommended 
values of p given in Table 7. 


Table 7. Probability of starting a serious fire with 
an M50 IB.* 


Height in ft 

5 

Occupancy in % 

15 25 35 

45 

7 to 19 

0 

0.02 

0.05 

0.10 

0.15 

20 to 29 

0 

0.01 

0.03 

0.05 

0.07 

30 to 39 

0 

0 

0.02 

0.03 

0.04 

♦Combustible-roof, 

European 

industrial 

buildings. 




Similarly to the M47 study, the relation of p 
to structural class of building was determined 
(all combustible-roof structures). Single-story 
small buildings, larger buildings with small 
spans, and larger buildings with spans above 
75 ft have p values of 0.07, 0.05, and 0, respec¬ 
tively. 

Data on noncombustible roof buildings were 
not available to an extent permitting determi¬ 
nation of p. 

Ove7^all Damage Prediction. An attempt to fit 
the data by a pair of simplified vulnerability 
equations, one for combustible-roof buildings 
and one for noncombustible buildings, was not 
successful (EWT-li). 

Direct-Hit Effects of 500-lb GP Bomb (EWT- 
3f and EWT-Jf.). Calculation of expected total 




































90 


TESTING AND EVALUATION OF INCENDIAHIES 


damage was carried out in each of two ways. In 
the first, the actual number of counted hits on 
the target was used to predict damage. In the 
second, actual observed number of hits was re¬ 
placed by a probability of hitting using the 
average density of bombs over the site rectan¬ 
gle. The corresponding equations developed are: 

g = A {l-[i-(pE+qM)/Ar‘j (la) 

and g = A {i} (ib) 

in which g = total damage area, 

A =plan area of target, 

p = probability of HE bomb to start 
serious fire = 0.17 (See E\\T-3b), 

£ = expected area of extent of an individ¬ 
ual fire. Depends on roof type. For 
combustible-roof buildings, E = A. 

For other buildings E (in 1,000’s of sq 
ft) = 35 X (l-e-‘/3»). 

g = l-p, 

M=HE structural MAE (See E\VT-2f), 

/z = observed number of direct hits, 

Z) = density of bombing, number of bombs 
per unit area. 

Note that g. A, E, and M are to be expressed 
in the same units. The above equations apply 
only to single-story fire divisions consisting of 
one building unit. For modifications to allow for 
multiple-story buildings and composite fire di¬ 
visions, see original report. 

A comparison of observed and expected dam¬ 
age, based on structural class of buildings, in¬ 
dicates an overall average error of 6 per cent 
when equation (la) is used. As expected, when 
actual counted number of hits is replaced by 
the use of an average attack density D, the 
average error in prediction of results increases. 
On 13 attacks it is 11 per cent. 

Miscellaneous. In EWT-lk the requirements 
for adequate pre-attack, attack, and post-attack 
photographic cover are discussed. 

The experience of the AN-23 group in ob¬ 
taining suitable data and the conflicting views 
held in various circles on inadequate evidence, 
led to the outline of a program of control at¬ 
tacks (described in NDRC Memo. No. A109N, 


OSRD Report No. 5034) designed to .settle 
some of the outstanding que.stions in choice of 
airborne weapons. 

Analysis of Incendiary Attacks on 
Japanese Cities 

The information on which this analy.sis is 
based was obtained from the Joint Target 
Group, Air Intelligence, Army Air Forces, and 
from the Operations Analysis Section, Twen¬ 
tieth Air Force. This information was prelimi¬ 
nary in nature and subject to revi.sion on the 
basis of ground observations. 

The data cover the fir.st 27 attacks on Japa¬ 
nese cities during the period from January 3 to 
June 19, 1945, which have already been sum¬ 
marized in Table 4 of Chapter 1. 

hicendiaries Used. The total tonnage of 
bombs dropped on these cities was 48,000 tons, 
of which 47,000 (97.4 per cent) were incen¬ 
diary bombs. Out of 281 sq mi of built-up area 
in these cities, 107 sq mile (38 per cent) were 
burned out completely. Seventy-flve hundred 
B-29’s attacked these targets in order to deliver 
the 48,000 tons of bombs; 2,500 B-29’s bombed 
visually and 5,000 bombed using radar, mostly 
on night raids. 

The tonnage of bombs dropped through 
June 19 was less than one-half of the total in¬ 
cendiary tonnage dropped on Japanese urban 
areas until the cessation of hostilities. Detailed 
data regarding these latter raids are not yet 


Table 8. Summary of munitions used in destroy¬ 
ing Japanese city areas, January 3 to June 19, 1945. 


Bomb 

Cluster 

Tons dropped 

G of total 

AN-M69 

E28, E36, M19 

25,000 

53.0 

AN-M47 


12,000 

25.4 

AN-M50 

M17 

9,000 

19.1 

AN-M76 

. . . 

1,000 

2.1 

M74 

M20 

200 

0.4 


available. Attacks made subsequent to June 19 
were on cities of less than 200,000 population. 

Table 8 is a summary of the munitions used 
in destroying these Japanese city areas up to 
June 19, 1945. 

Strategij, Tactics, and Operatioml Results. 
A brief description of the general strategy and 







ANALYSIS OF ATTACKS ON ENEMY TARGETS 


91 


operational results during this period of large- 
scale incendiary attacks follows. 

1. During January and February 1945, three 
small, high-altitude precision, daylight attacks 
were made on Nagoya, Kobe, and Tokyo. 800 
tons of AN-M69 incendiaries in E6R2 clusters 
were dropped on these three raids, resulting in 
a total damage of only 1 sq mile burned out. 
Post-raid photos of these raids indicated ex¬ 
cessive scattering of the incendiary bombs on 
the target. This was probably due to the ab¬ 
normally high winds prevailing from 20,000 to 
30,000 ft over Japan and the relatively poor 
aimability of the E6R2 cluster. The low tonnage 
of bombs probably permitted effective fire fight¬ 
ing. 

2. Following the small-scale incendiary raids, 
five big night raids were made during the period 
of March 9 to 18 on Tokyo, Kobe, Nagoya, and 
Osaka. These raids were made at low altitude, 
with each individual plane dropping its bombs 
on the target by radar. Ninety-five hundred tons 
of all types of incendiaries were dropped on these 
five raids, destroying a total of 26.4 sq miles 
(360 tons dropped per sq mi destroyed). These 
raids proved the vulnerability of the large 
Japanese cities to incendiary attack, and it was 
indicated that the raids would have to be made 
at low altitude in order to obtain a high degree 
of accuracy and with large tonnages of bombs 
in order to saturate the target and nullify fire¬ 
fighting efforts. 

3. Following the five big night raids, there 
was a delay of 1 month before the next incen¬ 
diary raid due to a lack of incendiary bombs at 
Guam. 

4. On April 13 and 15 three large-scale night 
raids were made on the Tokyo area from low 
altitude employing saturation bombing tactics. 
Forty-two hundred tons of AN-M69 and AN- 
M47 incendiaries were used on these raids and 
destroyed 20.8 sq miles of the city area (200 
tons dropped per sq mile destroyed). These 
raids were made possible by the arrival of a 
shipload of incendiaries at Guam consisting of 
approximately 80 per cent AN-M69 and 20 per 
cent AN-M47 bombs. 

5. Following these 3 night raids, another 
delay of 1 month ensued, again caused by a 
shortage of incendiaries at Guam. 


6. Beginning May 14, super raids, 500 planes 
each, were made on the 5 largest Japanese cities 
of Tokyo, Nagoya, Yokohama, Osaka, and Kobe. 
In an attempt to confuse the Japanese anti¬ 
aircraft defenses, these raids were made both 
during the day and night and varied from low 
to medium altitudes. It was the opinion of JTG 
that fire fighting was probably abandoned by 
the Japanese air-raid defenses during these 
raids. 27,500 tons of all types of incendiaries 
dropped on these raids resulted in 48.6 sq miles 
of damage (565 tons dropped per sq mile de¬ 
stroyed) . 

7. After June 15, the large cities of Japan 
were considered to be burned out and no fur¬ 
ther incendiary raids were conducted on them. 
The focus of attack was shifted to cities be¬ 
tween 200,000 and 400,000 population. Between 
June 17 and 19, about 1,000 tons each of AN- 
M69 and AN-M47 incendiaries were dropped 
on Kagoshima, Omuta, Hamamatsu, Yokkaichi, 
Toyohashi, Fukuoka, and Shizuoka. These raids 
were all made at night from low altitude and 
employing saturation bombing tactics. Most of 
the built-up area of each city was burned out 
on the first raid, about l^^ to 2 sq miles in each 
city. 

8. From June 19 until August 10, attacks 
were centered on cities under 200,000 popula¬ 
tion because of the burning out of the larger 
cities. These raids were made mainly at night 
and from low altitudes. Plane losses during this 
period were negligible. 

Observations concerning the tactics and con¬ 
ditions surrounding the raids include the fol¬ 
lowing. 

1. The rapid development of smoke during 
daylight attacks made precision bombing even 
from medium altitudes most difficult. This 
smoke in some instances obscured the target in 
5 min, indicating exceedingly rapid fire de¬ 
velopment. Since these raids were conducted 
over a period of 1 to 1^/i hr and used formation 
bombing, the formations following the lead 
planes frequently were forced off course in order 
to obtain a bearing on the target. This resulted 
in the bombs landing as much as 2 to 4 miles 
away from the target. For example, during the 
May 14 raid on North Nagoya, only 14 per cent 
of the bombs released fell within 4,000 ft of 



92 


TESTING AND EVALUATION OF INCENDIARIES 


the assigned aiming point. Of the total of 12,000 
clusters dropped, 64 per cent fell within the 
city, 17 per cent fell outside the city, and 19 
per cent were unaccounted for. In this par¬ 
ticular raid the area which received the heaviest 
concentration of bombs was approximately 
2,000 ft away from nearest aiming point and 
was relatively unsettled farming and manufac¬ 
turing area. 

2. The effect of rapid smoke obscuration of 
the target during daylight raids on formations 
following the lead plane at an average altitude 
of 18,000 ft is shown in Table 9. 

Table 9. Accuracy of day incendiary missions. 

Average dis¬ 
tance of 

% of bombs within bombs from 
Period of attack i mile 1 mile 2 miles target* 


First quarter 

27 

55 

20 

4,300 ft 

Remaining quarters 

13 

35 

38 

5,300 ft 

Whole 

17 

41 

30 

5,000 ft 

♦Excluding bombs falling 

more 

than 2 miles 

from 

target. 


3. Data regarding the accuracy of night in¬ 
cendiary missions employing individual radar 
bombing are given in Tables 10, 11, and 12. 


Table 10. Accuracy of night incendiary missions. 


Location 

of 

cities 

Radius of circle 
containing 50% 
of ident. 
patterns (CEP) 

Per cent of identified 
patterns which fell within 
2,000 ft 4,000 ft 6,000 ft 

Inland 

Coastal 

6,250 ft 

4,000 ft 

8 24 50 

18 50 75 


It appears from the data in Table 10 that the 
accuracy achieved on coastal cities was sub¬ 
stantially higher than that achieved on inland 
cities, probably because of the greater accuracy 


Table 11. Accuracy of night incendiary missions. 


Per cent of identified patterns 
which fell within 4,000 ft AP 

Altitude in feet 

7,500-8,500 

9,500-11,000 

15,000 

Coastal cities 

58% 

50% 

33% 

Inland cities 


26% 

16% 


of radar in delineating between water and land, 
as compared to areas completely surrounded by 
land. 

The data in Table 11 indicate that the ac¬ 
curacy of bombing on night incendiary missions 


decreased significantly with an increase in alti¬ 
tude. 

The data given in Table 12 confirm that the 
first quarter of the attack achieved a signifi- 

Table 12. Accuracy of night incendiary missions. 

Period Radius of circle Per cent of identified 

of which contained patterns which 

attack 50% of the fell within 

ident. patterns 2,000 ft 4,000 ft 6,000 ft 
_(CEP)__ 

First 

quarter 4,200 ft 23 49 72 

Remaining 

quarters 5,500 ft 8_33_60 


cantly higher accuracy than succeeding quar¬ 
ters, which phenomenon was first noticed in 
the precision daylight missions. The severe 
thermals encountered by the planes over the 
target after fires have been set may offer an 
explanation. 

It is generally believed that the effect of 
natural ground wind on fire propagation during 
these attacks was negligible in comparison with 
the tremendous draft created by the fires. For 
instance, on one raid in Tokyo there was re¬ 
ported a 70 mph ground wind in the city. Never 
in the history of the Tokyo weather observatory 
had there been a wind over 55 mph during that 
month. In general, the average wind over most 
of these Japanese urban areas varies from 10 
to 15 mph. 

Efficiency of AN-M69 Bomb. The most reli¬ 
able estimate of the minimum bomb load re¬ 
quired to accomplish substantially complete 
(80 per cent) destruction of typical Japanese 
dwelling areas is about 125 tons per sq mi, as 
shown in the table following below. These raids 
are discussed in greater detail in the following 
sections. The minimum bomb load was deter¬ 
mined by excluding those areas which were 
supersaturated with bombs and excluding that 
part of the bomb load which was dropped 
on supersaturated and unsettled areas. Areas 
chosen for analysis were residential in which 
between 50 and 100 per cent destruction oc¬ 
curred, in order that a threshold value of bomb 
load required for 80 per cent destruction of 
residential areas (20 to 80 per cent roof cover¬ 
age) could be determined. 



















ANALYSIS OF ATTACKS ON ENEMY TARGETS 


93 


Minimum 

tons 

incendiaries 

per 

sq mi of 

Total residential 


City 

Raid 

Tons of incendiary 
dropped 

area 

destroyed 

area 

required for 

date 

AN-M69 

AN-M47 

sq mi 

80% damage 

Nagoya 

5/14 

2,679 

0 

3.1 

160 

Osaka 

3/13 

1,782 

56 

6.6 

125 

Kagoshima 

6/17 

476 

360 

2.0^ 

1./ ^ 


Toyohashi 

6/19 

558 

426 

120 avg 

Shizuoka 

6/19 

531 

375 

2.3J 


North Nagoya Raid, May IJf, 100 Per Cent 
AN-M69. This raid was the only large-scale, 
daylight, 100 per cent AN-M69 attack on a 
Japanese city. Strike photos were available to 
permit a reasonably good analysis of the bomb- 
fall location^^ and pre-raid and post-raid damage 
photos have been analyzed for the extent of 
damage to various areas. Since most of the 
other large incendiary raids were either made 
at night with few strike photos or else employed 
a mixture of incendiary bombs, it is believed 
that this raid is probably the best source of 
data for a direct analysis of the efficiency of the 
AN-M69 bomb. 

Possible errors in this analysis, however, 
limit its accuracy to about ± 50 tons per sq 
mile. These errors include (1) only 80 per cent 
of the bomb falls were able to be plotted, (2) 
the plotted location of a given bomb fall is esti¬ 
mated as varying up to 2,500 ft from the true 
location, and (3) this raid was conducted using 
formation bombing at five different aiming 
points located between previously burnt-out 
areas and farmland which resulted in numerous 
bomb falls landing in these waste areas. Also, 
in view of the relatively poor bombing accuracy 
on this mission (only 6 out of 42 plotted forma¬ 
tion bomb falls fell within 4,000 ft of the as¬ 
signed aiming point), it is probable that the 
concentration of bombs within the target areas 
was not uniform but spotty, thus leading to 
bomb requirement values in excess of the true 
tonnage required. 

In summary, the conditions under which the 
Nagoya raid was carried out and the analysis 
made, make the 160 tons per sq mile value more 
likely to be higher than the true value. The 
subsequent analyses tend to confirm this state¬ 
ment. 

Osaka Raid, March 13, 97 Per Cent AN-M69. 
This raid was the first large-scale raid on Osaka, 


and thus has the advantage over the Nagoya 
raid of striking virgin target areas. The raid 
analysis made by JTG^^ which led to the bomb 
requirement value of about 125 tons per sq mile 
may be summarized as follows: This raid was 
made at night, with all planes bombing indi¬ 
vidually using radar, a condition which should 
result in a normal distribution of bombs about 
the aiming point. With no strike photos avail¬ 
able, a computation of the density of damage in 
circular areas about the mean center of damage 
was made. The values obtained indicated a good 
correlation with the normal distribution curve. 
Then, assuming that the density of bomb fall 
paralleled the density of damage, and that the 
center of damage coincided with the center of 
bomb fall, it was found that 125 tons per sq mile 
of M19 clusters (of AN-M69 bombs) was ade¬ 
quate to insure over 80 per cent destruction of 
Japanese city dwelling areas, about 40 to 80 per 
cent roof coverage. 

This indirect analysis of AN-M69 fire-raising 
efficiency appears sound in principle, and may 
offer a more accurate solution than the direct 
analysis of the Nagoya raid, considering all 
the errors possible in trying to locate each 
bomb fall precisely. The values of 160 and 125 
tons per sq mile obtained by the two methods 
are not, however, significantly different, and 
may be considered confirmatory. 

Kagoshima, Toyohashi, and Shizuoka Raids, 
June 17, 19, 57 Per Cent AN-MG9, US Per Cent 
AN-MU7. As a further check on AN-M69 fire- 
raising efficiency, an attempt was made to 
analyze raid results on smaller cities. Most of 
these raids involved the use of several types of 
incendiaries, and thus are not strictly com¬ 
parable with the Osaka and Nagoya raids. This 
analysis was undertaken for the raids on Kago¬ 
shima, Toyohashi, and Shizuoka using data on 
bombing accuracy from the Operations Analy¬ 
sis Section, XXI Bomber Command.-^*^-The 
method of analysis employed was similar to 
that used for the Osaka raid: Bomb distribution 
was assumed to follow the normal distribution 
curve, since these raids were made at night 
using radar individual bombing. Exact values 
for the density of bombs were obtained from 
OAS, e.g., the circular probable error for this 
type of bombing has been found to be 6,250 



94 


TESTING AND EVALUATION OE INCENDIARIES 


The aiming points for these raids fortu¬ 
nately coincided with the centers of damage; 
thus it could be assumed that the aiming points 
coincided with the center of bomb density. 
Damage to various areas around the aiming 
points was estimated from post-raid photos. 
Calculations for the three raids have been 
averaged in the following table. 


Radius of 
annulus about 
aiming point, ft 

Annulus 
area, 
sq mi 

Area 

burned out 
in annulus, 
SQ mi 

Bombs 

Striking 

annulus 

area, 

tons 

(clustered) 

Tons of 
bombs 
per sq mi 
damaged 

0-2000 

0.45 

0.43 

146 

340 

2000-4000 

1.35 

0.95 

146 

169 

4000-5000 

1.02 

0.40 

74 

185 


Since large areas in the outer annuli were 
not built-up but comprised mountainous and 
farming areas, a further series of calculations 


c Unpublished data from Joint Target Group (JTG). 


were made to limit the bomb requirement to 
residential areas which showed more than 20 
per cent roof coverage. 


Radius of 
annulus about 
aiming point, ft 

Built-up 
annulus 
area, 
sq mi 

Built-up 

area 

burned out, 
sq mi, % 

Bombs 

striking 

built-up 

area, 

tons 

(clustered) 

Tons of 
bombs 
per sq mi 
damaged 

0-2000 

0.44 

0.43 98 

143 

330 

2000-4000 

1.08 

0.92 85 

117 

123 

4000-5000 

0.51 

0.35 69 

37 

106 


The bomb-requirement value of about 120 
tons per sq mile for 80 per cent destruction of 
residential areas is, of course, based on the 
mixed bomb load of 57 per cent AN-M69’s and 
43 per cent AN-M47’s, and as such is not 
strictly comparable with the Osaka and Na¬ 
goya values. However, this analysis tends to 
confirm the order of magnitude of the previous 
values. 


’L 




Chapter 4 

PORTABLE FLAME THROWERS 


INTRODUCTION 

T he use of portable flame throwers as they 
are thought of today dates back to World 
War L These early models used a fuel mixture 
of a heavy and volatile oil which was propelled 
by compressed gas. At the start of World War 
II, few experiments had been made on the 


existed and that development should be under¬ 
taken. 

In this chapter, the NDRC contribution to 
the Portable Flame Thrower Program is sum¬ 
marized. As an expedient, the initial step con¬ 
sisted of redesigning the inefficient Ml port¬ 
able flame thrower in order that thickened fuel 
as well as unthickened fuel could be used. 



HYDROGEN CONTROL VALVE 


SHIELD SPARK CONTROL' 


HYDROGEN VALVE 


HYDROGEN TANK 


FUEL HOSE 


RELEASE 


HANDLE 


FOR 


HIGH-PRESSURE 
PROPELLANT TANK 


VALVE 


Y VALVE 


BATTERY AND COIL¬ 


FILLING PLUG' 


FUEL TANK' 


/REGULATOR 
/HIGH-PRESSURE VALVE 


FUEL TANK 


Figure 1. MlAl portable flame thrower. 


weapon, but the German army used them suc¬ 
cessfully against strongly held positions in the 
1940 invasion of the Lowlands. With the United 
States entry in the war and the beginning of 
close jungle warfare, interest in flame throwers 
increased. A report of the Ad Hoc Committee on 
Flame Throwers in June 1942 showed that a 
limited interest in portable flame throwers 


Realizing the limitations of the Ml model, 
or any improved model designed in the same 
manner, a development program was begun on 
an entirely different design. From this develop¬ 
ment work emerged the E2 flame thrower of 
Standard Oil Development, and E3 flame 
thrower of the Chemical Warfare Service. Com¬ 
parative tests of the E2 and E3 by the using 


95 





96 


PORTABLE FLAME THROWERS 


Services resulted in standardization of the E3 
as the M2-2. 

As a result of the British development of the 
Snapshot model, a 1-shot flame thrower, work 
was undertaken on similar models by both Di¬ 
visions 3 and 11 of NDRC. The end of World 
War II interrupted completion of the develop¬ 
ment work on this type of model. 


^2 MlAl FLAME THROWER 

Introduction 

When the Chemical Warfare Service’s Ml 
portable flame thrower gave evidence that the 
advantage of thickened fuel was not being at¬ 
tained, the Standard Oil Development Co. was 
directed in July 1942, under Contract OEMsr- 
390, to undertake modifications of the flame 
thrower in order that the weapon might suc¬ 
cessfully be used with either thickened or un¬ 
thickened fuel.i It was stated that these changes 
were to be few in number and simple in design 
to avoid the creation of extensive procurement 
problems (Fig. 1). In using thickened fuel, 
tests of the Ml flame thrower revealed that the 
optimum pressure for maximum range was not 
being attained and the pressure drop in the 
system was excessive. This condition suggested 
changes in both the pressure regulator and 
piping system. 

Description of Modifications 

Regulator. To increase the operating pressure 
from 275 psi to from 350 to 375 psi, the pres¬ 
sure regulator was adjusted by resetting the 
adjusting screw, thereby increasing the spring 
tension on the regulator diaphragm. In addi¬ 
tion, the relief valve in the regulator was ad¬ 
justed for 400 to 430 psi discharge pressure. 
This required using a thicker release button 
which resulted in additional compression of the 
relief valve spring. It was found that the re¬ 
stricted flow of pressured gas through the regu¬ 
lator resulted in a gradual drop in pressure in 
the fuel tank while firing. Increased flow ca¬ 
pacity was obtained by enlarging the openings 
in the regulator valve seat and the seat holder.^ 


Fuel Discharge Valve. Pressure gauges in 
the fuel line and gun tube, when using thick¬ 
ened fuel, indicated excessive pressure drop, 
100 psi, through the whistle type valve used as 
the fuel discharge valve in the gun unit. This 



Figure 2. Cutaway of quick-opening Y valve for 
MlAl portable flame thrower. 

valve was replaced with a Y-type, quick-open¬ 
ing valve which reduced the pressure drop to 
about 35 psi with thickened fuel (Figure 2).^ 



Figure 3. MlAl portable flame thrower firing 
unthickenecl fuel, range 20 yd. Note the intense 
flame and dense smoke. 


Performance 

Tests with unthickened fuels using both the 
standard Ml and the modified flame thrower 
showed that the mechanical changes outlined 
above did not impair performances (Fig. 3). 
Maximum ranges varied from 20 to 25 yd with 
either unit. Effective ranges depended on the 
target; for example, when neutralizing a Jap- 








E2 PORTABLE FLAME THROWER 


97 



Figure 4. MlAl portable flame thrower firing thickened fuel, range 60 yd. Note the breakup near the end 
of trajectory and the flame adhering to the rod. 


anese bunker, the maximum effective range was 
approximately 5 yd with either unit.^ 

Using 4 per cent Napalm thickened fuel, the 
modified unit gave an effective range of ap¬ 
proximately 20 yd (Fig. 4). This range repre¬ 
sented a considerable increase over that at¬ 
tained from an Ml flame thrower. On the basis 
of these tests the modified unit was standard¬ 
ized as the MlAl flame thrower." 


^ 3 E2 PORTABLE FLAME THROWER 
Introduction 

In an effort to eliminate undesirable char¬ 
acteristics still retained by the MlAl portable 
flame thrower, the Standard Oil Development 
Co. was directed in August 1942, under Con¬ 
tract OEMsr-390, to completely redesign the 
portable flame thrower.^ The new design as 
outlined by the Chief of Technical Division, 
Chemical Warfare Service, was to include the 
following characteristics. 


1. Decrease the weight of the unit for the 
same quantity of fuel, or increase fuel capacity 
for the same weight. 

2. Eliminate need of supplying to the field 
pressure cylinders of compressed nitrogen and 
hydrogen, and eliminate small flame-thrower 
pressure cylinders which had shown excessive 
leakage. 

3. Render ignition unit waterproof and more 
dependable. 

4. Reduce to a minimum the pressure loss in 
the fuel system, and establish optimum condi¬ 
tions for use with thickened fuels without im¬ 
pairing use of unthickened fuels. 

5. Eliminate need for two-man operation and 
improve overall ease of operation and porta¬ 
bility. 

The portable flame thrower E2 was designed 
to accomplish these improvements, and was 
capable of effective, reliable, and convenient 
operation by 1 man (Fig. 5).'^ The unit was 
constructed largely of aluminum alloy and was 
light in weight, had a large fuel capacity vary¬ 
ing from 3 to 6 gal depending on the permissible 





98 


PORTABLE FLAME THRO\^ ERS 



PRESSURE VALVE 


PRESSURE REGULATOR 


TANK CARRIER 


FUEL 

TANK 


PRESSURE TANK 


REAR GRIP 


FRONT GRIP 


PNEUMATIC 
FUEL VALVE 


BARREL 


NOZZLE 


ASSEMBLY 


GASOLINE 


SPRAY 


ASSEMBLY 


ELECTRICAL 

IGNITRON 

ASSEMBLY 


Figure 5. E2 portable flame thrower. 


load, and used either thickened or liquid fuels. 
Either nitrogen or compressed air could be 
used for propelling the fuel. Reliable ignition of 
the fuel was accomplished by an atomized gaso¬ 
line torch ignited by an electric spark. Table 1 
compares the characteristics of the E2 and 
MlAl. 


Table 1. Comparison of E2 and MlAl. 


Description 

Overall weight, lb 
Complete apparatus, 

MlAl 

E2 

empty 

Complete apparatus. 

34.5 

30 

filled (approx) 

Fuel unit 

63 

67 

Gross capacity, gal 

5 

6.5 

Fuel capacity, gal 

4.5 

6 

Shape 

Recommended operat¬ 

Dual tanks 

Single tank 

ing pi-essure, psig 
Pressure tank 

375 

240 

Shape 

Cylindrical 

U shaped 

Capacity, cu in. 
Recommended operat¬ 

157 

270 

ing pressure, psig 
Resistance to shatter¬ 

1800 to 2000 

1800 

ing 

Early tests 

Resistant to 

Gun unit 

showed 
tendency to 
shatter 

shattering 

Weight complete, lb 
Fuel discharge valve. 

9 

9 

type 

Y or slide ball 

Pneumatic Y 

valve 

valve 


Description 

MlAl 

E2 

Igniter fuel 

Compressed 

Atomized 

Primary ignition 

hydrogen 

gasoline 

Type 

Electrical 

Electrical 

Battery type 

Multiple 

Wet cell 

Battery voltage 

3 

2 

Duration of fire, sec 

10 

11 

Field supplies 

Napalm 

Napalm 


thickener. 

thickener. 


motor gaso¬ 

motor gaso¬ 


line, air 

line, air 


compressor, 

compressed 

hydrogen 

compressor 


Description 

Ta7ik U7iit. The tank unit (Figure 6) com¬ 
prised the following principal parts:® 

1. A single aluminum fuel tank of 6.5 gal 
gross capacity, equipped with a brass fuel inlet 
plug containing a frangible safety disk. 

2. A high-pressure aluminum U tank (partly 
surrounding the fuel tank) with a capacity of 
270 cu in. of compressed nitrogen or air, 
equipped with a valve for pressuring (similar 
to the type used in pressuring tires). 

3. A high-pressure valve which released the 
compressed nitrogen or air from the pressure 
tank to the fuel tank and was operated by a 
control lever easily accessible to the operator. 

4. A pressure regulator which maintained 










E2 PORTABLE FLAME THROWER 


99 





Figure 6. Rear view of E2 portable flame thrower 
in position. Note narrow silhouette smaller than 
operator’s shoulder. 

a constant pressure of nitrogen or air over the 
fuel during discharge. Initially the regulator 
was slightly larger but similar in principle to 
the MlAl regulator. However, failures oc¬ 
curred because of the loosening of the bonded 
synthetic rubber insert; a dome-type regulator 
was later substituted. 

5. A tank carrier which secured the tank 
unit to the operator’s back and consisted of a 
canvas back pad, shoulder and waist straps, 
and a quick emergency release mechanism for 
dropping the tank. The carrier was designed 
under advice from the Quarter Master Corps 
and tests, carried out at the Harvard University 
Fatigue Laboratory, showed that there was no 
significant difference in metabolic cost between 
the fully loaded MlAl and the equally weighted 
E2. 

A high tensile strength aluminum alloy was 
utilized in the construction of the tank unit. 
It was shown that such vessels could be satis¬ 
factorily fabricated by commercial production 
methods. Tests conducted by the Aluminum 
Company of America, using sodium chloride 


and peroxide as the corroding medium, showed 
that the alloy was not subject to inter-granular 
attack under pressure of 2,000 psi for 8 weeks 
at temperatures of 80 to 100 F, and that no 
effect was evident under contact with Napalm 
thickened gasoline after 3 weeks at 170 F. The 
pressure vessels, after undergoing pressures to 
2,000 psi, were also demonstrated by test to be 
shatter-proof when pierced with .30 cal armor¬ 
piercing ammunition at various representative 
sections. 

Gun Unit. The gun unit comprised the fol¬ 
lowing principal parts 

1. Two flexible hoses: the large hose con¬ 
veyed fuel from the fuel tank to the gun barrel 
and was equipped with a quick-disconnect 
coupling; the small hose conveyed compressed 
air from the high-pressure tank to the fuel- 
discharge valve and gasoline atomizer. 

2. A Y-type plug fuel-discharge valve (on 
breech end of gun tube) which released the fuel 
through the gun at the time of firing. The valve 
which had an aluminum cast body and stainless 
steel parts was operated by a trigger which 
opened a pilot valve and in turn allowed com¬ 
pressed air or nitrogen to actuate the valve di¬ 
rectly. A safety was provided for the trigger. 

3. A gun tube made of %-in. aluminum pipe 
with a special discharge nozzle. The tube sup¬ 
ported the ignition assembly and discharged 
through a cylindrical ignition chamber. 

4. An ignition assembly consisting of a gaso¬ 
line spray which supplied atomized gasoline 
(the same principle as the common nasal spray) 
to ignite the fuel as it was propelled from the 
barrel, and a waterproof high-tension electrical 
system consisting of a rechargeable wet-cell 
storage battery of the same size as a flashlight 
dry cell, vibrator, coil, condensers, and switches. 
The high-tension spark initially ignited the 
gasoline spray and remained in operation dur¬ 
ing the shot. A trigger mechanism, provided 
with a safety, simultaneously operated the 
gasoline spray and the electrical system. 

Performance 

A summary of the E2 firing test using 4 per 
cent Napalm (Gardner consistency of 90 to 
175 g) is given on the next page. 





100 


PORTABLE FLAME THROWERS 



Figure 7. Piston model of expendable flame thrower. 


Firing at 15 degrees elevation with a tail wind of 
4.5 to 10.2 mph, atmospheric temperature 32 to 47 F. 



Min 

Max Average 

Ignition of rod in air, % 

70 

95 

90 

Ignition of fuel on ground, % 

90 

95 

93 

Range, center of deposit, yd 

54 

65 

60 

Spread of fuel on ground, yd 
from 10 to 90% 

15 

33 

24 

Fuel discharge, gal/sec 

0.47 

0.52 

0.5 

Emptying of fuel tank, 

% fuel remaining after firing 

1.5 

4.5 

3.0 


Comparative tests of the E2 portable with 
the E3 portable unit developed concurrently by 


CWS were carried out. On the basis of these 
tests, which indicated the greater potentialities 
of cartridge ignition over the gasoline-electric 
ignition and the more rugged construction of 
the E3 gun, the E3 unit was standardized as 
the M2-2. However, the recommendation was 
made by the Infantry Board that aluminum 
fuel and air tanks be used in conjunction with 
the E3 gun (cartridge ignition), since the re¬ 
sulting lighter weight for the same amount of 
fuel, or increased capacity for the same weight, 
seemed advantageous.”- 





ONE-SHOT EXPENDABLE FLAME THROWER 


101 


ONE-SHOT EXPENDABLE FLAME 
THROWER 

Introduction 

The development of 1-shot expendable flame 
throwers for use with self-igniting fuels 
was undertaken in May 1944 under Contract 
OEMsr-242. During investigation of phospho¬ 
rus-phosphorus sesquisulfide eutectic (EWP) 
as a flame-thrower fueP^ and the evaluation of 
its casualty-producing properties, it became 
necessary to provide a means of ejecting the 
fuel, and thus the general objectives of the 
project included the design of a small, expend¬ 
able flame thrower adapted to the speciflc prop¬ 
erties of EWP fuel, and serving as a prototype 
for further development into an acceptable mili¬ 
tary weapon. 

The need for a special design arose from the 
fact that the use of self-igniting fuels in any 
standard flame thrower adapted for conven¬ 
tional thickened gasoline would lead to con¬ 
siderable difficulty and hazard, especially in 
filling the tanks. On the other hand, full ad¬ 
vantage could be taken of the special properties 
inherent in such fuels by their employment in 
a simple, small, prepackaged expendable device, 
which would require no refilling, but would be 
discarded after use. 

Such an instrument was designed and built, 
and with the aid of this flame thrower the casu¬ 
alty-producing properties of EWP were evalu¬ 
ated in physiological experiments. While the 
one-shot expendable flame thrower was not de¬ 
veloped beyond the experimental stage, the 
principles embodied in the device appeared to 
be sound for the purpose intended. 


Description 

Piston Model. The expendable flame thrower, 
illustrated in Figure 7, consisted of a steel shell 
approximately 4 in. in diameter and of 1 gal 
capacity, terminating at one end in a 1/4 in. 
nozzle for the ejection of the fuel, and at the 
other end in a percussion-breech assembly con¬ 
taining a cartridge, charged with a slow-burn¬ 
ing cordite propellant. A hollow piston placed 



Figure 8. Collapsible tube model of expendable 
flame thrower. 




























































102 


PORTABLE FLAME THROWERS 


between the breech and the main body of the 
shell served to transmit the pressure created 
by the burning cordite to the fuel, which was 
thus expelled from the flame thrower. On ac¬ 
count of the chemical nature of the fuel, no 
provision for ignition was required, the fuel 
igniting spontaneously immediately upon con¬ 
tact with air. The nozzle of the flame thrower 
was sealed with a frangible metal diaphragm 
which was broken by a cutting disk actuated by 
the pressure of the fuel; it was further pro¬ 
tected by a threaded shipping cap. 

Collapsible Tube Model. Another design is 
illustrated in Figure 8. In this design, the pis¬ 
ton was replaced by a collapsible tube contain¬ 
ing the self-igniting fuel. The collapsible tube 
of approximately 1 gal capacity, originally made 
of sheet lead, was ultimately manufactured of 
cottonfabric reinforced neoprene sheet¬ 
ing. Tubes of this material, strengthened with 
metal rods and cemented to the nozzle member, 
were adopted as standard and used in all fuel 
evaluation and range work. The modified design 
incorporated a 'Xc-in. nozzle and an improved 
percussion device for setting off the cordite 
propellant. 

Propelknit. The propellant powder found to 
give the best and most consistent range was a 
special modified, restricted-burning, Russian- 
type cordite, which was used in the form of a 


single grain 1.5 in. long by 1.26 to 1.55 in. in 
diameter. This powder was contained in a de¬ 
tachable combustion chamber connected to the 
main flame-thrower chamber through a small 
orifice about 0.1 in, in diameter, which served 
as a pressure regulator. The combustion cham¬ 
ber, in addition to the cordite propellant, also 
contained a black powder primer and a percus¬ 
sion cap. 

^ Performance 

Although some difficulty was always experi¬ 
enced with non-uniformity of propellant per¬ 
formance, the collapsible tube model gave fairly 
consistent center-of-deposit ranges, varying 
under different conditions from 50 to 70 yd for 
unthickened EWP fuel, and attaining 86 to 90 
yd with thickened fuels. The ejection time for 1 
gal was approximately 2 sec with a 'Ko-in. 
nozzle. The piston model gave considerable diffi¬ 
culty and was really never very successful. If 
this development had been carried further to 
a field model stage, it appears that the collapsi¬ 
ble tube model had more promise. 

In a parallel development, the Allegheny Bal¬ 
listics Laboratory of Division 3, NDRC devel¬ 
oped a piston type, 1-shot portable flame 
thrower, designated E16, which was about to 
go into production when World War II ended. 



Chapter 5 

MECHANIZED FLAME THROWERS 


INTRODUCTION 

T he development of long-range, large-ca¬ 
pacity flame throwers installed in armored 
tanks was a slow process. In 1942 the Ad Hoc 
Reviewing Committee, after reviewing the 
needs of the Services, concluded that only port¬ 
able flame throwers were definitely required 
and that the need for long-range mechanized 
flame throwers was problematical. This indi¬ 
cated a divergence from thought in England 
and Canada, where the mechanized flame 
thrower was regarded as a potentially impor¬ 
tant weapon. Notwithstanding the conclusions 
of the Ad Hoc Reviewing Committee, NDRC 
began some studies on large flame throwers 
which were subsequently demonstrated to the 
using Services. These demonstrations gave rise 
to increased interest in the potentialities of 
large flame throwers, with the result that in 
1943 Model Q, developed by Standard Oil De¬ 
velopment Co., was installed in an M5A1 light 
tank. Continued testing and demonstrating led 
to the initiation of several projects on the de¬ 
sign of flame guns in armored tanks. 

Originally the development was on the in¬ 
stallation of flame throwers in the M5A1 light 
tank, with the main armament removed. When 
the M5A1 became obsolete, work was begun on 
modifying the M4 medium-tank series for in¬ 
stallation of a large flame thrower. In the first 
models the main armament was replaced by 
the flame gun. However, in subsequent develop¬ 
ments toward the end of World War II the main 
armament was retained, and the flame gun was 
mounted coaxially with it. Besides the develop¬ 
ment of flame throwers in tanks, the U.S. Navy 
had a unit designed and built for installation in 
landing craft. 

In this chapter a review of the NDRC mech¬ 
anized flame thrower developments is presented, 
including such developments as were carried 
out by the Services with NDRC acting as en¬ 
gineering consultants. In order to follow the 
flame-thrower developments in this country and 
in others. Table 1 below summarizes the prin¬ 


cipal characteristics of all mechanized flame 
throwers. 


5 2 models a, b, c, and d flame throwers 

Introduction 

As a consequence of an NDRC group meeting 
at MIT on March 3, 1942,^ work was begun 
jointly by Factory Mutual Research Corp. (Con¬ 
tract OEMsr-167), Massachusetts Institute of 
Technology (Contract OEMsr-21), Gilbert and 
Barker Manufacturing Co. (Contract OEMsr- 
470), and Standard Oil Development Co. (Con¬ 
tract OEMsr-390) on the design and construc¬ 
tion of a large experimental flame thrower des¬ 
ignated as Model A. This unit, having a 1-in. 
nozzle, was modeled after the smaller British 
Ronson Lighter flame gun, but with the feed 
system changed to provide automatically inter¬ 
rupted firing in order to prolong firing time at 
high discharge rates. 

Following the construction and testing of 
Model A, Model B was designed but never built. 
This was followed in turn by Model C, which 
was sent to Shell Development Co. for testing, 
and by Model D, a simple experimental single¬ 
shot flame thrower. Although none of these 
models ever passed beyond the experimental 
stage, the experience gained in their develop¬ 
ment later made the rapid development of 
Model Q possible. 


Model A 

Flame-Thrower System. Model A consisted of 
a flame gun, high-pressure feed accumulator, 
low-pressure feed storage, and a high-pressure 
feed pump. The flame gun (Figure 1) was an 
automatic axial nozzle or pintle valve (seat di¬ 
ameter 1.4 in.) which was opened by fuel pres¬ 
sure against a 2-in. diameter piston and closed 
by adjustable spring action. 

The fuel flowed from the low-pressure stor- 


103 


104 


MECHANIZED FLAME THROWERS 



age tank of 65-gal capacity to a gasoline engine- 
driven Sundstrom multicylinder high-pressure 
feed pump, thence to the high-pressure feed ac¬ 
cumulator of 10-gal capacity, and finally in in¬ 
termittent bursts, to the flame gun. This type of 
pump was later found to be unsuitable for 
thickened liquids, and a Moyno rotor pump was 
substituted.-’ ^ 

Operation. Fuel was pumped at a steady rate 
from the low-pressure tank to the high-pressure 
accumulator under a gas cushion. The desired 
volume and pressure of the initial gas cushion 
was supplied by means of a compressor or inert 
gas bottles. The gun valve was spring-loaded 
to release at the desired pressure, release being 
accomplished by pumping fuel against the gas 
cushion into the high-pressure accumulator until 
the hydraulic force on the gun-valve piston 
was equal to the force of the spring normally 
holding the valve closed. This unseated the 
valve, after which additional hydraulic pressure 
acting upon the face of the valve aided in forc¬ 
ing the valve rapidly away from the nozzle 
opening. When sufficient fuel had been released 
to drop the gas cushion pressure about 20 per 
cent, the gun spring force exceeded the hy¬ 
draulic force on the valve stem and piston, 
and the valve closed. The frequency of gun- 
valve operation and fuel ejection depended 
upon the capacity of the high-pressure ac¬ 
cumulator and the rate at which it was refueled. 
In the experimental model the fuel pump ca¬ 
pacity permitted a maximum of only 2 shots 
per min of 1,000 psig maximum pressure. 

Performance. Tests showed that with un¬ 
thickened fuels the 1-in. nozzle caused an in¬ 
creased range about 75 yd over that obtained 
with the YiQ-in. nozzle of the Ronson unit (30 
to 40 yd). Thickened fuel gave effective ranges 
of 100 to 110 yd and the addition of powdered 
lead in methacrylate-thickened fuel gave effec¬ 
tive ranges up to 190 yd. At the time these 
ranges were obtained (low for a 1-in. nozzle) 
the importance of a straight section at the 
nozzle of a gun using thickened fuels was not 
realized."^ 

After testing it was apparent that certain 
weaknesses existed in the design; namely, a 
more satisfactory pump had to be developed 
and a faster valve action was required. 



























































PiPPHPBIPliWft 


Table 1.— 

-CHARACTERISTICS AND PERFORMANCE OF FLAME THROWERS—U. S. MODELS 

1 

Designation 

E2 

E4-5 

M3-4-E6R3 

E-12R2 gun 

E7-7 (E7-M5 AL) 

E12-7R1 

(E12-7R1 in M4-A1) 

2 

Developer 

CWS—(EA) 

u. s. 

M2 tank #8 

CWS—Edgewood 

TT S 

CWS(EA) 

U. S. 

CWS (EA) 

U. S. 

Built by NDRC—SOD 

U. S. 

NDRC—SOD 

U. S. 

3 

4 

Nationality 

Vehicle 

M4 tank series 

M4 A1 & M4 A3 
medium tank 

M4 A1 tank 

MS A1 light tank 

M4 A1 medium tank 


External silhouette 

Fuel system 

Gun 



M4 A3 M4 A1 tank 

M4 A1 tank 

75-mm. howitzer 

75-mm. rifle 

5 

6 

7 

E2 

E4 (24 gal) 

E5 (Modified E3 port¬ 
able with spark ignition) 

M3 8z; M4 

E6R3 

E4 R4—4R5 

E12 R2 

E7 

E7 

E12 

E7 R1 (extended nozzle 
in dummy 75-mm, 
rifle barrel) 

8 

Mount 

M2 tank 

In place of lower front 
M.G. 

Periscope (1) 

Turret periscope 

Turret 

Turret 


Flame*Thrower Data 





Flame-Thrower Data 


9 

Nozzle diameter (inches) 

i 1 

TT 

1 

A t tV 

1 

0.5 

2 0 

0.375 0.5 0.75 

2 

10 

Inlet diameter (inches) 

7(1) 7(1) 



15 

15 

11 

Included angle of convergence (degrees) 

30 



12 

Length nozzle straight section (diameters) 

3 3 

0 



10 

85 (approx.) 

13 

14 

Rate of firing (U. S. gal per second) 

Gun elevation (degrees) 

1.8 & 2.8 
-8 to +12 

0.8 (approx.) 

Same as bow machine 

0.7 1.0 1.2 

-20 to +24 

1 

-17 to +19 

2.4 

-10 to +30 

1.1 2.2 4.4 

-12 to +25 

15 

Gun traverse (degrees) 

360 

gun 

Same as bow machine 
gun 

90R to 45L 

105R 60L 

360 

360 

16 

Fuel valves—type 

Modified needle (2) 

Pistol type, needle 

Pintle 


Poppet (mushroom) 

Poppet (mushroom) 

17 

Location relative to nozzle 

At tip 

type, pintle 

Front end of barrel 

Front end of barrel 


17.5" upstream (1) 

17.5" upstream (1) 

18 

Opened by 

Manual operated toggle 

Squeezing pistol trigger 

Air-opened 


Air pressure 

Air pressure 

19 

Closed by 

linkage 

Manual operated toggle 

after releasing safety 
Release of trigger 

Spring closed 


Spring (+oil pressure) 

Spring (+oil pressure) 


linkage 

spring action 





20 

21 

Total capacity fuel tanks—U, S. gal—Gross 

Net 

120 

24 

22 

50 

47 

10/25 

112 

105 

297 

285 

22 

Number of fuel tanks 

2 

1; additional tank can 

2 

1-10 or 1-25 

5 

3 



be mounted over 








transmission 



Series connected 

Series 

23 

Description and arrangement of tanks 


16rx28rcyl. O. D. 

Cyl.—parallel conn. 


24 

Location and orientation fuel tanks 


Right-Sponson shelf 

M3 Sponson 
mount 


Vertical in basket 

2 horiz. in hull 

1 vert, in basket 





Horiz. M4 transmission 








mount 



325/350 

25 

Fuel tank operating pressure—psig 

240 to 300 

350/375 

375dz 

375 

340 to 380 

26 

Fuel propellant 

Nitrogen 

Air 

Air 

Air 

Air or nitrogen 

Air or nitrogen 

27 

Total capacity propellant tanks—cu ft 

660 (free air) 

0.6 (approx.) 


0.24 or 0.7 

4 

12.8 

28 

Number of propellant tanks 

3 

1 

2 

1 

21 (+2 to expel 
secondary fuel) 
Cylindrical—parallel 

7 

29 

Description and arrangement of tanks 

Parallel conn. 

9f"x2ir Cyl. O. D. 

Cyl.—similar to E4-5 

Cylindrical 

Cylindrical—parallel 

30 

Location & orientation of propellant air tanks 

Horiz. on rear deck 

Above and to one side 

Above and to one side 

Above & to side of 

20 vert. 3 horiz. 

6 horiz. in hull 



of fuel tank 

of fuel tank 

fuel tank 

in basket 

1 vert, in turret 

31 

Propellant initial pressure psig 

2000 

1800/2100 

1800/2100 

1800 

2000 

2000 

32 

Type secondary fuel 

None 

None 

None 

None 

Gasoline, kerosene, etc. 

Gasoline, kerosene, etc. 

33 

Secondary fuel pressure psig 



400 to 440 

450-540 i #520/530 for 

i"& i" 

34 

Type ignition 

HT spark 

H.T. electric spark 

Atom jet— 

Atom jet— 

Electric high-tension 

Electric high-tension 

35 


electric spark 

electric spark 

spark 

spark 

Ignition fuel 

Propane 

i pt. gasoline 25/30 psig 

Gasoline 15/30 psig 

Gasoline 

Gasoline, air atomized 

Gasoline, air atomized 

36 

Igniter air supply 

Induced 

Electric blower 

Air bottle 

Air under press, tank 

Induced 

Induced 

37 

Independent igniter operation 

Yes, trigger switch 

No 

No 


Yes 

Yes 



in handle 







Vehicle Data 





Vehicle Data 


38 

Tracked 

Yes 

M4 tank 

Yes 


Yes 

Yes 

39 

Armored 

Yes 

Yes 



Yes 

Yes 

40 

Amphibious 

No 

No 

No 


No 

No 

41 

Approximate combat weight—tons 

FT only—1.0 

35 

35 


18 

35-38 (est.) 

42 

Turret 

Standard 

Standard 


Slightly modified 

Standard 

43 

Number in crew 


5 

5 


3 

4 

44 

Armament ("X" turret) .30-cal. machine guns 


1-T 

1-T 


2 (1-T) 

2 (1-T coaxial) 

45 

46 

.50-cal. machine guns 


1-T 

1-T 


None 

1(T) (AA) 

37-mm rifle 


None 

None 


None 

None 

47 

48 

75-mm rifle 


1 

1 


None 

None 

Gun displaced by flame gun 

37 mm 

Bow-machine gun 

None 


37 mm 

75 mm 



.30 cal. 






Performance 





Performance 


49 

50 

51 

52 

T uel or Gardner Consistency 

Oils 7i%Al stearate 

4.2% Napalm 


75/125 Gardner 

Napalm 7% 

8% Napalm 

Discharge rate—U. S. gallons per second 

1 


1 

2.4 

|"-1.1; i"-2.2; i"-4.4 

Kange yards (10° elevation—5-10 mph tail wind) Effective 

nozzle 

60 


65/80 

105 to 115 

88 no 125 

Maximum 

45 to 58 75 (4001) 


40/60 


125 to 135 

105 130 150 


Notes 





Notes 




(1) 9° & 10.5° also tried 


(1) Mounted in spe- 


(1) Relative to dis- 

(1) Relative to dis- 



(2) Tried gate value at 


cially designed peri- 


charge opening of tap- 

charge opening of tap- 



first which gavedrooling. 


scope holder installed in 


ered nozzle, inlet to 

ered nozzle, inlet to 




assistant driver's door 


straight section. 

straight section. 





hatch or turret peri- 


4 units completed by 

20 units constructed 





scope mount. 


Jan. 1945, in combat. 

Nov. ’44-Apr. '45. 17 






Luzon P. I. April 1945. 

sent to Pacific. None in 







Construction by Cadil- 

combat prior V-J Day. 







lac Div. and SOD, 1st 

Construction by M. VV. 







unit tested by CWS 

Kellogg Co., 1st units 







and Armored Board. 

tested by CWS and 
Armored Board. 


M5-4 (E12-7R1) 

-E7 (USN Mark I) 

E14-7R2 (E7-LVT-A1) 

-E8 

1 

NDRC—SOD 

NDRC—SOD 

NDRC—SOD 

NDRC—KLAAS 

2 

U. S. 

u. s. 

U. S. 

U. S. 

3 

M4 A1 or M4A3 

Integral unit 

LVT-Al amphibious 

M5 A1 tank 

4 

medium tank 

for LCVP, LCM, LCT 

tank 

Shielded mantlet 


Same as E12-7R1 

Cylindrical tube 

75-mm. howitzer 

5 

E12 R1 

USN—Mark I 

E14 

E8 

6 

Same as E12-7R1 

E7 

E7R2 

7 

Same as E12-7R1 

On top of fuel tank 

Turret 

Special small turret 

8 




Flame-Thrower Data 


Same as E12-7R1 

0.5 

0.5 

0.5 0.625 0.75 

9 

Same as E12-7R1 
Same as E12-7R1 

2 

15 

2 

15 

2.75 

Constant acceleration 

10 

11 



curve 

12 

Same as E12-7R1 

10 

10 

8.8 

Same as E12-7R1 

2.4 (approx.) 

2.4 

3.5 

13 

Same as E12-7R1 

-10 to +30 

-10 to +30 

— 7 to +25 

14 

Same as E12-7R1 

90 left to 90 right 

120 left to 120 right 

90 left to 90 right 

15 

Poppet (mushroom) 

Poppet (mushroom) 

Poppet (mushroom) 

Primary poppet 
Secondary pintle 

16 

17.5" upstream 

17.5" upstream (1) 

17.5" upstream 

Primary upstream 
Secondary at nozzle 

17 

Air pressure 

Air pressure 

Air pressure 

Primary air pressure 
Secondary fuel pressure 

18 

19 

Spring (+oil pressure) 

Spring ( +oil pressure) 

Spring (+oil pressure) 

Primary spring & fuel 



pressure 





Seondary spring 


291 

220 

210 

240 

20 

275 

200 

200 

210 to 215 

21 

3 

1 

2 

2 

22 

Series 


Series connected 

Cyl.—series connected 

23 

2 horiz. in hull 

Vert, above air bottles 

Vertical in hull 

Vertical in rt. 

24 

1 vert, in basket 



compartment 


325/350 

350-425 

325-350 

400 approx. 

25 

Air or nitrogen 

Air or nitrogen 

Air or nitrogen 

Air 

26 

27 

28 

12.6 (earlier) 11.5 (later) 

7 

10.5 

7 

8.4 

8 

9.3 

4 

Cylindrical—parallel 

Cylindrical—parallel 

Cylindrical—parallel 

2 sets of 2 in parallel 

29 

conn. 

Horiz. hull. 

Horiz. in row 

Side of hull 

2-Sponson—2 in 

30 

1-vert.-basket 

under fuel tank 

horiz.—2 each 

F.T. comp. 

31 

2000 

2000 

2000 

2000/2500 

Gasoline, kerosene, etc. 

Gasoline, kerosene, etc. 

Gasoline, kerosene, etc. 

Gasoline, kerosene, etc. 

32 

520-540 

550 to 500 

500 to 550 


33 

Same as E12-7R1 

Electric high-tension 

Electric high-tension 

Electric high-tension 

34 

spark 

spark 

spark 

35 

Same as E12-7R1 

Gasoline, air atomized 

Gasoline, air atomized 

Gasoline, vaporized 

Same as E12-7R1 

Induced 

Induced 

Yes 

36 

Same as E12-7R1 

Yes 

Yes 

37 




Vehicle Data 


Same as E12-7R1 


Yes 

Yes 

38 

^me as E12-7R1 

Front and sides 

Yes 

Yes 

39 

Same as E12-7RI 

1 Integral complete 

Yes 

No 

40 

Same as E12-7R1 

J 3-ton unit which can be 

19 

18 (est.) 

41 

^me as E12-7R1 

[placed in any suitable 

Slightly modified 

Replaced with fixed 

42 


[carrying craft or vehicle 

6 (2 in turret) 

turret 

43 

Same as E12-7R1 

3 

Same as E12-7K1 


3 (1-T coaxial 

3(2-7) 

44 

Same as E12-7R1 
Same as E12-7RI 
Same as E12-7R1 
Same as E12-7R1 

(Number of men in 

1 crew and armament 
[dependent on carrying 
[ craft or vehicle 

with F.T.) 

None 

None 

None 

37 mm 

None 

None 

None 

37 mm 

45 

46 

47 

48 




Performance 


Same as E12-7R1 

6/7% Napalm 

6/7% Napalm 


49 

J"-2.2, r-4.4 

2.4 

2.4 


50 

10-125 

105 to 115 

105 to 115 


51 

30-150 




52 




Notes 


Three hundred units 

21 units built by Kel- 

Prototype tested Fort 

Prototype tested at 


under construction by 

logg Lecourtenay used 

Ord. Built by Lima 

Edgewood summer 1944. 


Kellogg will have no 

by Navy at Palau. 

Locomotive. 



turret tank, other 

(1) Relative to dis- 

50 units under con- 



minor modifications. 

charge opening of tap- 

struction by M. W. 



(1) Relative to dis- 

ered nozzle, inlet to 

Kellogg. 



charge opening of tap- 

straight section. 

(1) Relative to dis- 



ered nozzle, inlet to 
straight section. 


charge opening of tap¬ 
ered nozzle, inlet to 




straight section. 



































































































































































♦ 


f 




k 


44 ** 





!«• 


4 







" A 

'I ▼ / 


. 

it V’' ' 





:'■ . .. ! .. *1 .' 1 


I’i f'.; .. 
> l&r#. Ma-.. 






,> 




; 7 : 


4 


I - 


i 


. •«■ r 


> - 

I 


« 




\ 


I 


f 


t 



f* 


. ♦ 





i 



1 











Table 1.—CHARACTERISTICS AND PERFORMANCE OF FLAME THROWERS—(Continued) U. S. MODELS 


-13 

-E9 

E13-13 

E13R1-13R2 

POA-CWS—H-1 

Satan 

T-33 




1 

NDRC—Shell 

NDRC—Std. of Ind. 

NDRC—Morgan 

NDRC—MIT 

CWS (POA) 

CW&—(POA) 

ORD—CWS 



, 

2 

Development Co. 


Construction Co. 



u. s. 

(NDRC-SOD) 





U. S. 

U. S. 

U. S. 

U. S. 

U S. 

U. S. 



. 

3 

Prototype gun only 

M5 A1 tank with trailer 

M4 A1 tank 

M4 A1 tank 

M4. M4 A1 & M4 A3 

M3 A1 It tank 

M4A3—E2 hull—new 



. . 

4 






turret 







M4 A1 dummy 75-mm 

M4 A1 dummy 75-mm 



Extended 75-mm 



.. 

5 



rifle 

rifle 



howitzer 






Compressor and tanks 

E13 

E13R1 


.. 

Series containers in 




6 


on trailer 





hull turret 





13 

E9 

E13 

E13R2 

Modified Iglehart- 

Modified Ronson 

E7R3 




7 





Ronson 







Test 

Experimental 

Turret 

Turret 

Turret in 75-mm tube 


Turret 




8 





Flame-Thrower Data 





Flame-Thrower Data 


0.625 

0.25 and 0.75 

0.375 0.5 0.625 

0.375 0.5 0.625 

19/32 


0.5 0.75 




9 

1.5 

2.25 3.125 

2 

2 

1.5/2 


2.0 




10 

90 & Curve rad. 

Approximately 30 

Curve 

Curve 

30 


15 




11 

8 

14 5 

4 3 2.5 

4 3 2.5 

0 


Approx. 40 




12 

3.5 (approx) 

0.75"—5.8 at 440# 


r-1.3 ^"-2.2 i".3.6 


1.5 (approx.) 

2,2 4.4 




13 

-15 to +43 

-6 to +37 

-10 to +25 

-10 to +25 

Same as 75-mm gun 

-15 to +18 

-IS to +45 




14 

360 

25 R and 25 L 

360 

360 

270 

180 

360 




15 

Pintle 

Pintle 

Pintle 

Pintle 

Pintle 


Poppet (mushroom) 




16 

At nozzle 

Between vert & horiz 

At nozzle 

At nozzle 

At nozzle 


17.5 upstream (1) 




17 


trunnion 










Fuel pressure 

Fuel pressure 

Fuel pressure 

Fuel pressure 

Fuel pressure 


Air pressure 




18 

Air pressure 

Air pressure + spring 

Air pressure & spring 

Air pressure & spring 

CO 2 pressure 


Spring 




19 

500 

1,200 


289 


170 

265 (approx.) 




20 

500 (approx) 

600 

315 

259 

290 


250 (approx.) 




21 

1 

1 

3 

3 (1 @ 74 gal, 

2 @ 107.5 gal) 

4 


4 




22 

Air in rubber bag 

Fitted with air driven 

Parallel conn. 

Parallel connected air 

Series connection 


Series connection 




23 


agitator 


in rubber bags 








On ground 

Horiz.—trailer 

Hull—horiz. 

74 gal in turret 

Hull—below basket (1) 


2 Horiz. hull: 2 turret 




24 



2-107.5 gal below basket 







500 (approx) 

475/500 

50/75 

300/350 at nozzle 

300/350 

180/250 

350 




25 

Air 

Air 

2 rams & compressed 

Air 

CO 2 (liquid) 


Air or nitrogen 




26 


80 

air 

6 gal & 11.12 cu ft 

9.36 

150 lb 






27 


1 

Turret-3 hull-6 

3 @ 3.12 cu ft 

3 


8 




28 


Space above oil in 

3000# Navy bottle 

Parallel 3,000# Navy 

, , 


Cylindrical parallel 




29 


main tank 


bottle 








Trailer 

Turret & hull 

1 in turret 

Right sponson 


7 horiz.-hull 1 vert. 




30 




2 in right sponson 



basket 






500 

2,000 

2,000 

850 at 70° F 


3.000 




31 


50% gasoline & 

Lube oil, gasoline, 

Lube oil. gasoline. 

Gasoline 


Gasoline, kerosene 




32 


SAE 30 

Diesel oil 

Diesel oil 








90 

400 

400 



500 




33 

Electric, high-tension 

Electric, high-tension 

Electric, high-tension 

Electric, high-tension 

Electric, high-tension 


High-tension spark 




34 

spark 

spark & hot wire 

spark 

Gasoline, air atomized 

spark 

spark 






Gasoline, air atomized 

Gasoline and SAE 30 

Gasoline, air atomized 

Gasoline sprayed 


Gasoline, air atomized 




35 


pressure atomized 

Main pressure tanks 






Air bottles 

Induced 


.. 


Induced 




36 

Yes 

Yes 


Yes 

Yes 


Yes 




37 





Vehicle Data 





Vehicle Data 



Yes 

Yes 

Yes 

Yes 


Yes 




38 


Yes 

Yes 

Yes 

Yes 


Extra armor of 




39 







M4A3E2 






No 

No 

No 

No 


No 




40 


Tank 18—trailer 13 

35-38 (est.) 

35-38 (est.) 

M4 A1 + 1.5001b 


Over 40 tons 




41 


Standard 

Slightly modified 

,. 


Special design 




42 




4 



5 




43 


Standard 


3—2 (1-T) 

2 (1-T coaxial) 


2 (1-T) 




44 


Standard 


1* 



1-T 




45 


Standard 





No 




46 


Standard 


76-mm rifle 

75 mm 


M6 (light) 




47 



75 mm 


None 




48 





Performance 





Performance 


2.5% Napalm 8% 

10% Napalm 500# 


8% Napalm 

r-2.2, 

6% Napalm at 
200/250# 

Napalm 





49 

35 135 

100/120 







50 

90 160 


95 107 

60/80 

60/80 





51 

90 150 



* * 






52 

Prototype built by 

Built by Merz Eng.- 

Fires 12 gal or two 

E13 gun modified by 

Notes 

S>xty-two built in 

24 built by POA com- 

Also to carry small 



Notes 


Grove Regulator tested 

Marmon Herrington. 

cylinders full in 4 to 6 

replacing Morgan yoke 

theater completed 

pleted May, '44. 

AP periscope-mounted 
flame gun in turret. 





with stationary fuel 

Tested by Std. Ind. 

sec. 

joint by more compmt 
swivel joint capable ot 

about January 1. 1945 





tank — first tested 



lor use in theater 


Unit under design by 





early 1944. 



replacing 

operations. 


ORD-CWS (with SOD 








mount. Prototype 

(1) Basket shortened 


Kellogg). 20 to be 








constructed by 
bour-Stockwell. 

♦Also carried 4 .45-ca!. 

and new floor installed. 


constructed with p)os- 
sible later increase. 

(1) Relative to dis- 








subm. g . . 



charge opening of tap- 








Nozzles interchui»k‘ • 



ered nozzle inlet to 








able. 



straight section. 






Designation 

Developer 

Nationality 

Vehicle 

External silhouette 
Fuel system 
Gun 
Mount 


9 

10 

n 

12 


13 

14 

15 


16 

17 

18 

19 

20 
21 
22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 


38 

39 

40 

41 

42 

43 

44 

45 

46 

47 

48 


49 

50 

51 

52 


Flame-Thrower Data 


Nozzle diam—inches 
Inlet diam—inches 

Included angle of convergence—degrees 
Length nozzle straight section—diam 


Rate of firing—U. S. gal per second 
Gun elevation—degrees 
Gun traverse—degrees 


Fuel valves—Type 

Location relative to nozzle 

Opened by 
Closed by 


Total capacity fuel tanks—U. S. gal—Gross 

Net 

Number of fuel tanks 
Description and arrangement of tanks 
Location and orientation fuel tanks 
Fuel tank operating pressure, psig 


Fuel propellant 

Total capacity propellant tanks—cubic ft 
Number of propellant tanks 
Description and arrangement of tanks 

Location and orientation of propellant air tanks 

Propellant initial pressure, psig 


Type secondary fuel 
Secondary fuel pressure, psig 


Type ignition 

Ignition fuel 

Igniter air supply 
Independent igniter operation 


Vehicle Data 


Tracked 

Armored 

Amphibious 

Approximate combat weight—tons 
Turret 

Number in crew 


Armament (‘‘T’' turret) .30-cal machine guns 
,50-cal machine guns 
37-mm rifle 
75-mm rifle 

Gun displaced by flame gun 


Performance 


Fuel or Gardner 

Discharge rate—U. S. gal per sec 

Range yds (10° elevation—5-10 mph tail wind) Effective 

Maximum 


Notes 



















































































































y 

10 

11 

12 


li 


14 

15 


16 


17 

18 


19 


20 

21 

22 


23 


24 


25 

26 


27 

28 


29 

30 


31 


32 

33 

34 


35 


36 

37 


38 

39 

40 

41 

42 


43 


44 

45 


46 

47 


48 


49 

50 

51 

52 



Designation 


Developer 

Nationality 

Vehicle 


External silhouette 


Fuel system 
Gun 


Mount 


Flame-Thrower Data 


Nozzle diam—inches 
Inlet diam—inches 

Included angle of convergence—degrees 
Length nozzle straight section—diam 


Rate of firing—U. S. gal per second 


Gun elevation—degrees 
Gun traverse—degrees 


Fuel valves—Type 


Location relative to nozzle 
Opened by 


Closed by 


Total capacity fuel tanks—U. S. gal—Gross 

Net 

Number of fuel tanks 


Description and arrangement of tanks 
Location and orientation fuel tanks 


Fuel tank operating pressure, psig 


Fuel propellant 


Total capacity propellant tanks—cubic ft 
Number of propellant tanks 


Description and arrangement of tanks 
Location and orientation of propellant air tanks 


Propellant initial pressure, psig 


Type secondary fuel 

Secondary fuel pressure, psig 


Type ignition 

Ignition fuel 


Igniter air supply 
Independent igniter operation 


Vehicle Data 


Tracked 

Armored 

Amphibious 

Approximate combat weight—tons 
Turret 


Number in crew 

Armament ('‘T” turret) .30-cal machine guns 


.50-cal machine guns 
37-mm rifle 
75-mm rifle 


Table 1—CHARACTERISTICS AND PERFORMANCE OF FLAME THROWERS—(Continued) FOREIGN MODELS 


Gun displaced by flame gun 


Pcrformuiicc 


h uel or Gardner 

Discharge rate—U. S. gal per sec 


Range yd (10 elevation—5-10 mph tail wind) Effective 
■—— -Maximum 


Notes 


Crocodile (trailer) 

PWD 

British 

Trailer towed by 
Churchill VII or M4 
tank 

Armored sheath 

Normal Wasp type 

Tank hull, left asst, 
drive (replace bow- 
machine; permanent 
installation) 

Wasp Mk II 
(formerly known as Mk 
II former Wasp Mk II 
now Mk I) 

British 

Universal Bren carrier 

Armored sheath 

WaspMK 

(Weight filled 2.0001b) 

Front of vehicle 

Salamander (No. I) 

PWD 

British 

M4 A4 or 3, or Churchill 

Armored sheath below 
75-mm dummy barrel 

Wasp IIA 

Turret-below 75-mm 

Salamander (No. II) 

Lagonda 

British 

Sherman medium tank 

Regular; dummy gun 
with FT nozzle 

Modern Wasp extended 
barrel (see Note 1) 

Inside dummy 75 mm 

Salamander (No. Ill) 

Lagonda 

British 

Sherman 

Regular FT nozzle in¬ 
side dummy 75-mm 
barrel 

Modern Wasp with ex¬ 
tended barrel inside 
dummy 75-mm barrel 

Salamander (No. Ill®) 
Alternatives “A" & “B” 
(similar to No. Ill) 

"A" Lagonda “B” 
British 

Sherman 

Salamander (No, IV) 

PWD 

British 

Sherman 

Wasp* IIA 

Turret; below 75-mm 
dummy in mantlet 





Flame-Thrower Data 



1.0 0.842 

0.6 0.76 0.9 (approx.) 

0.799 





3.25 3.25 

3.25 3.25 3.25 






30 30 

30 30 30 






3.5 4.1 







5.6 6.8 

2.4 (3.2) 4.4 6.8 

4.4 Intermittent or 

4.4 Intermittent or 

4.4 to 5.4 Intermittent 


4.4 Intermittent or 



continuous 

continuous 

or continuous 


continuous 

-9 to +15 

-14 to +25 

-10 to +25 

-10 +25 

-10 +25 


-10 +25 

15 right or left (30) 

25 left to 25 right 

360 

360 

360 


360 

Primary pintle 

Primary pintle 






(secondary electric 

(secondary electric 






contact pneum. gate) 

contact pneum. gate) 






At nozzle On trailer 

Nozzle Upstream 






Fuel Gas 

Fuel Gas 






pressure pressure 

pressure pressure 






Gas pressii re Ga s 

Gas Gas 






and spring pressure 

pressure pressure 






480 

120 (1-48 gal 1-72 gal) 

240 to 300 

320 

240 

140 160 

216 

430 

100 

240 to 275 



. . 


2 

2 

3 

2 

4 (1-28 gal, 2-69 gal. 

^/l-28gal ,/2-69gal 

2 Cylindrical 





1-38 gal) 

^\3-38gal '^\l-28gal 


Series 


Series, right to left to 

Series, charged with 5 

Cylindrical vertical 


Series 



lower tank 

HP air compressor on 

series 






drive shaft 




In trailer (Proof against 


2 in sponsons (2x78 gal) 

Longitudinal hull floor 

Turret basket 


Horizontal on hull floor 

7.9-mm A.P. shell; 


1 below basket (1x120 





Total wt 6 tons full) 


gal) 





300 

200 (180 to 250) 

300 

600 



300 

N 2 or flue gas 

CO 2 (liquid) (note 2) 

N 2 or flue gas 


CO 2 

CO 2 CO 2 or Na 

N 2 or inert gas (see 






(3.000 lb) 

note 1) 


40 lb 

4.5 



2 2 4 


5 

1 CO 2 or 2 inert gas 

6 (Ronson type) 


2 to 3; Electrically 


io 





heated evaporator 



Parallel with check 




Parallel 


No 

valve from each tank 







In trailer betw. fuel 


Behind assistant driver 


Turret 



tanks 


under base of turret 







basket 





3,000 

600 to 1,000 or 2,000 to 

3,000 




3,000 


3,000 






Gasoline 

Gasoline 

Gasoline 




Gasoline 

None 







Electric high-tension 

Electric high-tension 

Electric high-tension 




Electric spark 

spark 

spark (twin) 

spark 





Gasoline spray (0.1 sec 

Gasoline spray (0.1 sec 

Gasoline jet 




Gasoline 

at start of shot) 

at start of shot) (see 







Note 1) 






Yes 






No 

Yes 

No 

No 









Vehicle Data 



Yes 

Yes 

Yes 

Yes 

Yes 


Yes 

Yes 

Yes 

Yes 

Yes 

Yes 


Yes 

No 

No 

No 

No 

No 


No 

7 (trailer only) 

1 (FT equipment only) 

35-38 (est.) 




35-38 (est.) 

Standard 

None 

Standard 

Angular tank replaces 

Standard 


Standard, smaller turret 




turret basket & base 



basket, modified base 

Normal 

2 

5 

junction modified 

4 

4 


junction 

5 


None 

2 (IT) 

2 (1 bow. 1 turret) 

2 (1 turret right 


2 





mantlet) 




None 

1 (T) 

None 

None 




None 

None 

None 

None 



75 or 95 mm (T) 

None 

None 

Yes 

Yes 


None 

BESA. (7.92 mm) 

None 

75 mm 




75 mm 

6.5° Nozzle Elev. 




Perloriiiuiice 



Unstated Wind 







7.8 ■ 5.6 

6.8 






84 90 

80 100 120 






90 95 

140 150 

90 100 









Notes 



In production — used 

Canadian Wasp is sim- 

Prototype reported 

Note (1) Also flame gun 

3 to 5 hp required from 


(1) Cordite propulsion 

during invasion of 

ilar but has 70-gal fuel 

August 8, 1944. Several 

in loader's periscope. 

engine to drive pump 


under investigation. 

hranee. In a test of 

tank positioned across 

mo(lels, including varia- 

Requires 5 hp from 

during refueling only. 



l)ro<luction prototype 

and at rear of carrier. 

tions retaining 75-mm 

engine. (2) LP gas su))- 




1-26-44 firing 8 shots of 

Note (1) In MK 1 

rifle in vehicle, are 

plie(l from re.servoirs 




1 to 4 sec duration, 

gasoline spray is fed 

being considered. 

and recompressed by 




h RAS (448.4 sec. 06 

from positive servo- 


coinpre.ssor driven by 




5.5 C hall drop British 

operated pump linked 


tank engine after firing. 




standard), a discharge 

to trigger valve by gas 






rate of 4.4 U. S. gal 

pressure from separate 






per sec, ranges to center 

lank, whereas in Mark 






of maximum deposition 

II gasoline is fed from 






of 80 to 100 yd were 

carburetor gasoline 






obtained while heavy 

pump—Note (2) COj 






ground deposit, with 

evaporator uses water 






considerable burning, 

from both banks of 






ranged 70 to 120 yd. Ig- 

cylinders; designed for 






nition was practically 

2.S0 psi working pres- 






trouble f ree. A falling off 

sure. 






of range was noted on 







shots of 4 sec duration. 








Salamander (No. V) 


PWD 

British 

Sherman 


Salamander (No. VI) 


PWD 

British 

Sherman 


Non-pintle sleeve valve 
small and compact 


3.6 to 4.8 Intermittent 

or continuous 
--10 +45 

90 left and right (180) 


216 

2 

Cylindrical parallel 


Horizontal on hull floor 


N? or inert gas (same 
as for design IV) 


10 


Parallel 


3.000 


Cartridge fired 
automatically 
Cordite 


No 

No 


Yes 

Yes 

No 

35-38 

Smaller turret basket 


+ 100% of normal 

ammunition 


Yes + 40% of normal 
ammunition 
None 


Non-pintle sleeve v’alve 
small and compact 


Side of turret operated 
by turret gunner 
(Blister) 


Salamander (No. VII) 


PWD 

British 

Sherman 


Non-pintle sleeve valve 


Wireless base, 
co-driver’s seat 


Flame-Thrower Data 


3.6 to 4.8 Intermittent 
or continuous 
-70 +90 

360 


216 

2 

Cylindrical 


Horizontal on hull floor 


N 2 as in design IV 


10 

Parallel 


High-pressure bottles 
5 on each sponson 


3.000 


None 

Pyrotechnic 


P>Totechnic 


Yes 

Yes 

No 

35-38 

Smaller turret basket, 
modified base junction 


2 + 100% of 
ammunition 


1 + 40% of normal 
ammunition 
None 


Blister armored to nor¬ 
mal thickness. 


3.6 to 4.8 Intermittent 
or continuous 
-10 +45 

90 right and left (180) 


120 

6 (2 large, 4 small) 
Cylindrical 


Horizontal on hull floor 


N 2 or cordite (as for 
design IV) 


5 

Parallel 

5 on each sponson 


Automatic cartridge 


Vehicle Data 


Standard 


2 + 100% normal 
ammunition 


Yes + 40% ammunition 
None 


Performance 


Notes 


2 

3 

4 


9 

10 

11 

12 

Ti” 


14 

15 

16 


17 

18 


19 


20 

21 

22 


23 


24 


25 


26 


29 

30 


( 


31 


32 

33 


34 

35 


36 

37 


38 

39 

40 

41 

42 


43 


44 


45 

46 

47 


48 


49 

50 

51 

52 















































































































































JNFI 


Table 1.— CHARACTERISTICS AND PERFORMANCE OF FLAME THROWERS—(Continued) FOREIGN MODELS 


9 

10 

11 

12 


13 

14 

15 


16 


17 

18 

19 


20 


21 

22 

23 


24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 


36 

37 


38 

39 

40 

41 

42 

43 

44 

45 

46 

47 

48 

49 

50 

51 

52 


Designation 

Developer 

Nationality 

Vehicle 

External silhouette 
Fuel system 
Gun 


Mount 


Flame-Thrower Data 


Nozzle diam—inches 
Inlet diam—inches 

Included angle of convergence—degrees 
Length nozzle straight section—diam 


Rate of firing—U. S. gal per second 

Gun elevation—degrees 
Gun traverse—degrees 


Fuel valves—Type 


Location relative to nozzle 
Opened by 

Closed by 


Total capacity fuel tanks—U. S. gal—Gross 


Number of fuel tanks 
Description and arrangement of tanks 

Location and orientation fuel tanks 

Fuel tank operating pressure, psig 


Net 


Fuel propellant 

Total capacity propellant tanks—cubic ft 

Number of propellant tanks 

Description and arrangement of tanks 

Location and orientation of propellant air tanks 
propellant initial pressure, psig 

Type secondary fuel 
Se condary fuel pressure, psig 

Type ignition 
Ignition fuel 


Igniter air supply 
Independent igniter operation 


Vehicle Data 


Tracked 

Armored 

Amphibious 


Approximate combat weight—tons 
Turret 

Number in crew 

Armament ('•T” turret) .30-cal machine guns 

.50-cal machine guns 
37-mm rifle 
75-mm rifle 


Gun displaced by flame gun 


Performance 

Fuel or Gardner 

Discharge rate—U. S. gal per sec 
ange yd ( 10 » elevation-S-10 mph tail wind) Effective 
“ Maximum 


Notes 


Salamander No. VIII 

PWD 

British 

Sherman 


Non-pintle sleeve 


In blister on 
turret side 


Like 

de¬ 

sign 

VI 


3.6 to 4.8 Intermittent 
or continuous 
-10 to -f90 
360 


100 


Cylindrical series 


Horizontal on hull floor 


N 2 or Cordite 
(as per design IV) 


High-pressure cylinders 
or Cordite 
Sponson 
3.000 


Modified base junction 
5 


2 100% normal 

ammunition 


Yes + 40% 
ammunition 


poamcpNiTAL 


Ronson 

Canadian 

Universal Bren carrier 
Cylindrical tube 
Ronson FXJL Mk IV 

Left of vehicle 


0.44 

1.75 

35 

0 


0.565 

1.75 

35 

0 


2 2.4 

-15 to -h20 
90 left to 40 right 


Primary: Secondary: 
gate pintle 


CO 2 

pressure 

Spring 


At nozzle 
Fuel 
pressure 
Spring 


72 


64 

2 

Series connected 


Rear of vehicle 


160 to 200 


CO 2 (Hq) (see note 2) 


40 lb 


Rear of vehicle 
600 to 1,000 


Gasoline 

None 


Electric high-tension 
spark (single) 

Gasoline spray (0.1 sec 
at start of shot, note 1) 


No 


Yes (universal carrier) 
Yes, hull 
No 


0.6 ton (flame-thrower 
equipment only) 
None 
2 


None 

None 

None 

None 


None 


FRAS, Marine Diesel, 
special 

50 40 to 45 80 


Early unit now obso- 
j fi . \ete. One of earliest 

mechanized flame throwers. (1) Positive displacement pump 
mechanically actuated from actuating arm. Pump fed by vehicle 
luei pump. (2) CO 2 evaporator uses water from left bank of 
cylinders only. Designed to withstand tank pressure of 180 psig. 


Rattlesnake Mk II 
Canadian 

Rattlesnake Mk II 
Prototype gun only 


0.5 


0.625 


2.25 


3.32 


-5 to +34 
18 left and 36 right 


Secondary: 

pintle 

At nozzle 
Fuel 
pressure 


Primary; 

Grove 
flexible 
Upstream 
Fuel 
pressure 
Air pressure Spring 


Experimental tank used 
for testing only—44 
U. S. gal 

V 


350 300 


f200 at base 
1 of nozzle 


Air 


1,800 


2,200 


None 

None 


Electric high-tension 
spark 

Premixed gasoline and 
air (below torch) 

(3 jets of 10 cc/sec) 

Yes 


Yes (universal carrier) 
Yes 


6 % 

2.25 3.32 

100 125±10(15®elev) 
150 


Prototype gun mounted 
on frame with experi¬ 
mental fuel tankage 
only. 

Report 4 August 1944. 


Frog Mk I 


Australian 

Matilda Mk IV or Mk V 


Frog Mk I 


1.125 

is 


Adder 

PWD 

British 

Sherman or Churchill 


Periscope rear of tank, 
not turret 


Flame-Thrower Data 


Adder 

PWD 

British 


Sleeve valve gun 
Wireless base 


Pintle 


At nozzle 
Fuel pressure 

Spring and fuel pressure 
acting on pintle con¬ 
trol piston 


250 


Parallel connection 
(see note 1) 

2 in sponsons, 

(1 below basket) 
(1 jettisonable) 


10 gal floating piston 
pump filled by fuel 
pumps 

Air compressed in 
pump jacket during 
filling 

Thirty-five sec 
required to fill cylinder 


Cylinder in basket 


Gasoline 

None 


Electric high-tension 
spark 

Gasoline spray at start 
of spark 


95 

115 


(1) Fuel pumped from 
reserve tanks to mam 
98-gal tank. 

25 built in late 1944 and 

mounted in Matilda 
tanks for Australians. 


3.2 

-45 to +45 
180 


Rear of tank outside 


Inert gas 


3,000 


Vehicle Data 


Yes 

None 


Performa nee 


3.25 


^ Notes 

Experimental gun (only 
preliminary specifica¬ 
tions available). 


1.6 Intermittent or 
continuous 
-10 to +45 
Limited only by line of 
hull and periscope vision 


Barracuda 

British 


Crocodile (design 
features) 

PWD 

British 

Cromwell (fast 
cruising type) 
Trailer, detachable 

Evolution of Barracuda 
with best features of 
others 


0.74 

2.5 


4.0 

-5 to +25 
±40 


30 


Standard 
Ronson type 

Right 

sponson 


60 


2 

Cylin¬ 

drical 

Right 

sponson 


Inert gas 


1 High 
pressure 


Inert gas 


6 Medium 
pressure 


Flash cartridge same 
as Wasp 


Yes Yes 

(Less 17 rounds 
ammunition) 


225 to 250 


CO 2 (Hq) (see note 1) 


variable 


German 
PZKW III 


Replace 50-mm cannon 
in simulated gun barrel 


-10 to +45 
180 


400 gal 


Fuel inside rubber bag 
being considered; also 
floating piston 
Trailer, armored, 6-ton 
castor wheel hitch 

400 lb 


0.394 

2 


German 
Vehicle towed 
self-contained 


On trunnions on spigot 
on top of fuel tank 


2 

3 

4 

5 

6 
7 


Flame-Thrower Data 


9/16 

ii 


Gate operated by piston 


At nozzle 

Fuel pressure on piston 
controlled by trigger 
Spring 


180 


2 (1-80; 1-10) 
Series connected 


Below basket 
Atmospheric 


1.75 

-10 to +30 
±45 


48 


42 

1 


Welded plate const. & 
sump 


Atmospheric 


9 

10 

11 

12 

13 

14 

15 


16 


17 

18 

19 


Cordite considered 


Gasoline 


Twin HT spark gaps 
continuous 

Gasoline from separate 
pressure tank 


0.65 (equipment only) 


Sir Speci.1 

50-55 75 120(#/in2) 


(1) CO* evaporator 
used water of both 
banks of cylinders; de¬ 
signed for 1,000-lb 
water pressure. 


Still experimental.Pyro¬ 
technic will be tried. 
Continuous 

Gasoline. FT fuel heated 
to 70 F oil jacket 


Yes; wheeled trailer 
Yes 
No 


None 


FT fuel #2 


150 (unbroken rod) 
300 


2-Stage centrifugal 
pump driven by 28 hp 
2 cylinder engine rated 
at 1.6 gal/sec at 
135 psig—220/250 
psig shut-off head 
Pump located in tank 
engine compartment 


Main fuel 
None 


Electric high-tension 
spark 

Fuel spray 


Mixture of fuel oil and 
creosote oil 

60 

80 


A number of these guns 
have been captured, 
some mounted in tanks, 
others in half-tracks 
and trailers. 


2^* & 32-stage 
centrifugal pump 
driven by standard 
DKW 1085 cu cm 
cylinder off at top 
Piston 2 stroke 3J x 3* 
Gas engine 


85/170 


Gasoline 
30 gal 


High-tension spark. 
Reliable 

Atomized gasoline 


Vehicle Data 


Ball bearing disc 
wheels without brakes 
6^ X 16^ pneumatic 
i tires No 7.5 mm 
fronted plate. 

And plate to protect 
operator’s head 
0.9 

No 


Performance 


Creosote (150#) 
WD gas oil (135#) 


35/40 

45/50 


30/35 

35/40 


Notes 


20 


21 

22 

23 


24 

25 

26 

27 

28 

29 

30 

31 

32 

33 

34 

35 


36 

37 


38 

39 

40 

41 

42 

43 


44 

45 

46 

47 


48 


49 

50 

51 

52 













































































































































Table 1—CHARACTERISTICS AND PERFORMANCE OF FLAME THROWERS—(Continued) FOREIGN MODELS 


1 

2 

3 

4 

5 

6 

7 

8 

Designation 

Developer 

Nationality 

Vehicle 

External Silhouette 

Fuel System 

Gun 

Mount 

German 

Ps Jo 38 

Strahlrohr 

German 

Pump* 

(Armored half-track) 









1 

2 

3 

4 

5 

6 

7 

8 


Flame-Thrower Data 





Flame-Thrower Data 





Flame-T hrower Data 


9 

10 

11 

12 

Nozzle diam—inches 

Inlet diam—inches 

Included angle of convergence—degrees 

Length nozzle straight section—diam 

14 mm (O.55'0 

5.5 

0 









9 

10 

11 

12 

13 

14 

15 

Rate of firing—U. S. gal per second 

Gun elevation—degrees 

Gun traverse—degrees 

21 

-5 to -i-35 

20L to 40R 

2.1 

-10 . . :t20 

80R to SOL 









13 

14 

15 

16 

17 

18 
19 

Fuel valves—Type 

Location relative to nozzle 

Opened by 

Closed by 

Hand operated 










16 

17 

18 
19 

20 

21 

22 

23 

24 

25 

Total capacity fuel tanks—U. S. gal—gross 

Net 

Number of fuel tanks 

Description and arrangement of tanks 

Location and orientation fuel tanks 

Fuel tank operating pressure, psi, ga. 

185 

185 

2 









20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

Fuel propellant 

Total capacity propellant tanks—cubic ft 

Number of propellant tanks 

Description and arrangement of tanks 

Location and orientation of propellant air tanks 

Propellant initial pressure, psi, ga 

See note 










26 

27 

28 

29 

30 

31 

32 

33 

Type secondary fuel 

Secondary fuel pressure, psi, ga 











32 

33 

34 

35 

36 

37 

Type ignition 

Ignition fuel 

Igniter air supply 

Independent igniter operation 

Cartridge 

Spark ignition of fuel jet 









34 

35 

36 

37 


Vehicle Data 





Vehicle Data 





Vehicle Data 


38 

39 

40 

41 

42 

43 

Tracked 

Armored 

Amphibious 

Approximate combat weight—tons 

Turret 

Number in crew 

Projector —37 § 










38 

39 

40 

41 

42 

43 

44 

45 

46 

47 

48 

49 

50 

51 

52 

Armament turret) .30-cal machine guns 

.50-cal machine guns 

37-mm rifle 

75-mm rifle 

Gun displaced by flame gun 











44 

45 

46 

47 

48 

Performance 





Performance 





Performance 


Fuel or Gardner 

Discharge rate—U. S. gal per sec 

Range yd (10° elevation—5-10 mph tail wind) Effective 

Maximum 

55-66 

Coal tar 

40 





•• 

• * 

• • 

• * 

49 

50 

51 

52 


Notes 

122 GPM. pump 231 
psi closed disch. pres¬ 
sure 190 psi open disch. 
press. (14-mm jet) 28 
hp FW 1101 DKW. 2 
cycle engine. Also 

captured was FT on 
armored FT. Vehicle 
SD.KFZ. 251/16 and 
FT trailer. 

♦Driven by 2-cylinder 
in-line engine. Vehicle 
has 2 flame guns, one 
on each side. 



Notes 





Notes 









































































































































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I. 


t 




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r..: 







MODELS A, B, C, AND D FLAME THROWERS 


105 


" ""* Model B 

IModel B consisted of a gun similar in prin¬ 
ciple to Model A, but with a nozzle valve de¬ 
signed to open and close rapidly during a very 
small part of the full operating cycle of the 
piston. A large spring behind the valve-operat¬ 
ing piston replaced the Model A gas cushion. 
However, calculations indicated that the design 
was impractical since for 1,000 psig maximum 
operating pressure a piston spring over 90 in. 
long, weighing 300 to 400 lb would be required. 
Model B design was therefore abandoned, and 
no units were built.- 

Model C 

Model C (Figure 2) was similar to Model A 
except that, despite the increase to 2-in. nozzle 
size, the weight of the valve stem was reduced 



Figure 2. Experimental assembly in Model C. 


considerably and an air cushion behind the 
valve stem was substituted for the valve piston 
spring. An air cushion behind a floating piston 
to the rear of the valve mechanism in the gun 
also was substituted for the Model A high-pres¬ 
sure accumulator. The maximum rearward 
valve travel was 3 in. with a dash pot included 
to prevent valve stem damage against a rear 
stop. It was expected that this design, like 
Model A, would operate with the valve opened 
automatically and intermittently at a rate de¬ 
pending on the pump. Since the open-valve flow 
rate was about 160 gal per sec, a fractional time 
open of 10 per cent or less was planned. 


With a few additional modifications. Model 
C2 (Figure 3) was sent to Shell Development 
Co. for further testing.^- 

Investigations at Shell revealed the follow¬ 
ing: 

1. The anticipated long range from the 2-in. 
nozzle was never realized, the range being of 
the order of 150 yd. 

2. Even if the hoped-for range had been ob¬ 
tained, Model C appeared to be much too large 
to be of practical interest. 


" " " Model D 

Model D was a simple experimental single¬ 
shot flame thrower. Fuel was ejected from the 
open nozzle by means of an internal compressed 
gas-operated piston, with no internal nozzle 
valve. Piston stop-sleeves of various lengths 
could be inserted in the fuel chamber to vary 
the quantity of fuel ejected (Figure 4). A quick¬ 
acting, air-actuated valve installed between the 
compressed-air storage tank and the air cham¬ 
ber in the gun behind the piston was designed 
to facilitate rapid piston operation and fuel 
ejection. In operation, a temporary plug was 
inserted in the gun-nozzle opening, fuel was 
charged into the nozzle chamber ahead of the 
piston, forcing the piston to the rear, and then 
sudden air pressure was applied behind the pis¬ 
ton to eject fuel from the weapon. Ignition was 
accomplished by firing through a continuous 
hydrogen flame inside a cylindrical chamber 
mounted in front of the flame gun nozzle. 

In addition to tests on thickened fuel of vary¬ 
ing Napalm concentration at different pres¬ 
sures, a number of tests were made ejecting 
thickened fuel in lightweight cotton or rayon 
socks. These socks were approximately 2-in. 
diameter tubing, closed at one end, and varying 
in length from 10 to 25 ft. In operation, the 
socks were telescoped compactly on a cylindrical 
sleeve, about 8 in. long, placed concentrically 
in front of the nozzle. The ejected gelled gaso¬ 
line entered the tubing which then stretched 
out in line of fire to its original length as it 
was carried through the igniter. In effect, the 
single shots thus fired were thrown out in cloth 
bags which prevented premature breakup of 




106 


MECHANIZED FLAME THROWERS 


fuel in the air, and hence greatly increased 
range (Figure 5). 

Performance. Without the sock, thickened- 
fuel ranges up to 170 yd to center of deposit 
were obtained with a 2-in. nozzle bore. 

Confining the fuel in a sock, which in effect 
increased the size of the gob, resulted in in¬ 
creased range. Thickened-fuel ranges up to 330 
yd were realized with a 2-in. nozzle when eject¬ 
ing the fuel in a sock at approximately 1,000 
psig pressure.'^ This indicated that improve¬ 
ments in range could be effected if a fuel could 
be made which would hold together and could 
be ignited after ejection in appreciable mass at 
a high velocity. Further work along these lines 
was discontinued on Model D to expedite de¬ 
velopment of a large flame gun. Model Q, more 
suited to mechanized installation. 


5 3 MODEL Q AND E7 SERIES FLAME GUNS 
Introduction 

As the need arose, the Standard Oil Develop¬ 
ment Co. in November 1942, under Contract 
OEMsr-390, began the design of a long-range 
flame thrower gun designated as Model Q and 
developed for mechanized installations.^® After 
the original prototype Model Q was built, the 
gun was modified, as a result of tests^^’^- and 
combat experience, into the improved Model Q 
(later designated as the E7), the E7R1, E7R2, 
and E20. However, although these later modi¬ 
fications included several refinements and irn- 
provements, the basic design of the original 
Model Q remained unchanged. In several in¬ 
stances, the gun design was altered slightly to 
make possible an installation in a specific vehi¬ 
cle, but in general there was very little differ¬ 
ence among the various models. To identify the 
gun model with the correct installation, the 
relationship is summarized below. 

Gun model Installation 

Q Trailer-mounted prototype 

E7 E7-7 in M5A1 light tank 

USN Mark I 

E7R1 M5-4 (E12-7R1) in M4A1 and M4A3 
medium tanks 

E7R2 E14-7R2 in LVT-Al amphibious tank 

E20 T-33 (E20-20) in M4A3E2 medium tank 


In the following discussion the E7 will be de¬ 
scribed in some detail, rather than the original 
Model Q, which it resembled closely. Later the 
various modifications of subsequent models will 
be given. For a complete detailed description of 
each model, the reader is referred to the refer¬ 
ences appearing in the bibliography. 


^ E7 Improved Model Q 

Introduction. The E7 flame gun^^, i4 consisted 
of the following integral parts (Figures 6 and 
7) : (1) nozzle, (2) gun body (vertical trun¬ 
nion), (3) trunnion elbows, (4) air chamber, 
(5) main spring housing, (6) main control 
valve, and (7) supplemental assemblies com¬ 
prising the pilot valve for gun actuation, and 
the atomizer valve for igniter operation. 

Nozzle. The bronze nozzle was bolted to the 
front flange of the gun body. The conical por¬ 
tion of the nozzle tapered from 2-in. ID at 
the entrance to 1 / 2 -in. ID (15 degree included 
angle), with a 5 in. long and 1 / 2 -in. ID straight 
section. The nozzle was encased in a cylindrical 
cover, the forward end of which comprised the 
ignition chamber. 

Gun Body and Trunnion Elbows. The gun body 
was a bronze casting housing the main fuel 
valve seat, which was a beveled stainless steel 
ring press-fitted in place. The gun body also 
housed a perforated, hollow brass cylinder 
through which secondary fuel (liquid gasoline) 
was forced under pressure (400 to 450 psi) to 
coat the exterior of the main flame-thrower fuel 
stream passing through the gun body. Attached 
to two diametrically opposed flanges on the 
sides of the gun body were the two trunnion 
elbows which carried main fuel into the weapon, 
supported the gun, and permitted its elevation 
and depression around special rotary joints. 
These rotary joints consisted of a machined 
sleeve (part of the trunnion elbow) which 
slipped inside the flange on the side of the gun 
body. The inside of the flange was grooved to 
hold a rubber 0 sealing ring which prevented 
fuel from leaking out. Each trunnion elbow 
was held in place by a split collar bolted to the 
gun body flange. 

Air Chamber and Main Spring Housing. The 




il GAS 

ADJUSTING OIL 
FUEL 


TO OIL SUPPLY 


Figure 3. Schematic diagram of Model C2. 
































































































































I 




• r 


' r 














i: 


ii 


Je®-^ <<k*3 .» ^ ■ .- *• ^ 


•C' 


^ 7 <> 






MODEL Q AND E7 SERIES FLAME GUNS 


107 


air chamber was a bronze cylindrical flanged 
casting, which carried and guided the main fuel 
valve and was bolted to the rear of the gun body. 
The main spring housing was a steel tube 



Figure 4. Cutaway view of Model D flame gun. 


which was in turn bolted to the rear of the air 
chamber, and held the main spring, the valve 
stop, and the breech nut. The valve stop, which 


limited the rearward travel of the valve, was 
a rod extending through the core of the spring. 

Main Control Valve. The function of the main 
control valve, which was a cast bronze dual 
control bolted over the air chamber, was (1) 
to admit high-pressure air (375 to 400 psi) to 
the main air chamber, forcing the main fuel 
valve backwards (open) so that the main fuel 
was expelled from the gun, and (2) to allow 
secondary fuel to flow into the forward gun 
body and thence through the perforated sec¬ 
ondary fuel cylinder to coat the main fuel. 

The rear section of the main control valve 
body contained two machined liners cut so that 
two separately sealed annular spaces were 
formed between the body and the liner. These 
spaces communicated with the interior of the 
valve by small holes drilled radially through the 
liners. Main air was supplied to the forward 
annular space and entered through the liner 
holes between two flanges on an internal sliding 



Figure 5. Flaming sock fired from Model D flame 
thrower. 


piston. The piston was held in the forward or 
closed position by a spring. Air delivered by 
the pilot valve entered a separate chamber in 
the forward end of the valve cylinder ahead of 
the piston forward flange, forcing the piston 
backward and compressing the spring. This 
movement caused the two piston flanges to 
straddle the liner holes to the two annular 
































































108 


MECHANIZED FLAME THROWERS 


spaces, and connected the main air inlet of the 
forward annular space with the air outlet of 
the rear annular space, which discharged into 
the air chamber and opened the main fuel valve 
in the gun. The forward end of the piston passed 
through an opening in the forward valve sec¬ 
tion (piston bonnet), which contained a valve 
port that was closed by the conical end of the 
piston. Secondary fuel entered one side of the 
bonnet and, when the piston was forced to the 
rear, flowed out through the forward end of 
the bonnet into the gun body. The rear opening 
of the bonnet through which the piston slid 
was made air- and gasoline-tight by a synthetic 
rubber 0 sealing ring in the piston bonnet par¬ 
tition. Similar sealing rings rode in grooves in 
the two piston flanges. 

Pilot Valve. The pilot valve was a small 


air for the main control valve. The pilot valve 
consisted of a valve body, cylindrical perforated 
liners, and valve body covers, as well as a slid¬ 
ing piston, piston sealing rings, and spring. 

Atomizer Valve. The atomizer valve was a 
dual purpose piston-type shut-olT in a small 
bronze cylindrical casting which supplied air 
and gasoline to the atomizer nozzle for the 
flame-thrower igniter. The valve body consisted 
of two sections, (1) the air body, which was 
identical with the pilot-valve body, and (2) 
the atomizer gasoline body, which was bolted 
to the forward end of the air body. An internal, 
two-piece sliding piston, opened manually and 
closed by spring, acted as an air valve at the 
rear and as a gasoline valve on the forward 
end. Synthetic rubber 0 sealing rings sealed 
the air from the gasoline chamber. 



SECTION A-A 


Figure 6. Sectional elevation of E7 flame gun. 


bronze cylindrical piston-type air shut-off valve. 
The function of this valve, which was manually 
actuated by trigger pressure against a sliding 
piston, was to supply high-pressure actuating 


Operation. The gun was fed through two 
diametrically opposed rotary trunnion elbow 
joints which permitted movement of the weapon 
in elevation or depression (—10 to +30 de- 


C 

























































































































MODEL Q AND E7 SERIES FLAME GUNS 


109 


grees). Horizontal movement of the E7 was 
permitted through a rotary joint in the vertical 
feed pipe over the main fuel container (U.S. 
Navy Mark I unit), or by traversing the turret 



atomizer 

CONTROL - 


MAIN CONTROL 
VALVE 


RIGHT TRUNNION 
ELBOW 


ATOMIZER 
AIR INLET 


ATOMIZER 


NOZZLE 


NOZZLE 


ATOMIZER 


GASOLINE 


VALVE 
SPRING HOUSING 
CYLINDER 

LEFT TRUNNION 
ELBOW 


Figure 7. E7 gun for M5A1 light tank. 

(E7-7 unit). Operating controls for the weapon 
were dual firing handles bracketed to the breech 
of the gun. These handles were also used to 
move the gun in elevation and (for the Mark 
I unit) traverse. Actuation of a trigger on the 
left handle closed an electrical switch send¬ 
ing high-tension current to dual spark gaps in 
the ignition chamber through which the flame 
gun fired, and actuated the atomizer valve send¬ 
ing gasoline and air through an atomizer nozzle 
into the ignition chamber as a spray around the 
spark gaps. This produced a blow torch flame 
for ignition of main fuel. Actuation of the 
trigger on the right firing handle operated the 
pilot valve, which opened the dual main control 
valve on the E7 gun. Opening of the main con¬ 
trol valve injected (1) air into the gun to open 
the main fuel valve and (2) secondary fuel into 
the weapon to coat the main fuel. 


5.3.3 Modifications of the E7 

E7R1. The development of a flame-thrower 
unit for an M4 tank required minor changes in 
the gun design.Inasmuch as the E7 flame 
gun was designed with a relatively short nozzle 
unsuited for use in an extended dummy gun 
tube simulating the 75-mm rifle installed in 
medium tanks, it was necessary to add a nozzle 


extension. To meet the requirements, the ta¬ 
pered nozzle was redesigned with a %-in. bore 
flanged outlet. To this tapered nozzle was bolted 
a short %-in. bore extension. Interchangeable 
long extensions of hi. and % in. were pro¬ 
vided with flanged inlets for bolting to the short 
extension. 

The hand-operated trigger mechanisms for 
the gun controls were replaced with foot con¬ 
trols. A right foot button switch in front of the 
turret gunner actuated a solenoid which opened 
the pilot valve. An emergency foot pedal could 
also be used to actuate the pilot valve in case of 
solenoid or local electrical failures. Ignition of 
the main fuel rod ejected from the flame-gun 
nozzle was initiated by pressing the gunner’s 
left foot pedal prior to depression of the fuel- 
firing button. The pedal mechanically actuated 
the atomizer valve and closed the electrical cir¬ 
cuit to dual spark gaps in the ignition chamber 
downstream of the flame-gun nozzle outlet. 

The flame gun was moved in elevation by 
means of an elevating handwheel, and moved in 
traverse with the vehicle turret. 

E7R2. For installation of the E7 flame gun 
in the LVT-Al, both V 2 -in. and %-in. bore inter¬ 
changeable nozzles were provided, unchanged 
in length. 

Dual-firing handles were bracketed to the 
weapon for direct elevation or depression. De¬ 
pressing a button in the right handle actuated 
a solenoid which opened the pilot valve. De¬ 
pression of a right foot pedal actuated the 
igniter identically with the E7R1 system. The 
gun moved in traverse with the turret. 

E20. The E20 had a medium length, inter¬ 
changeable nozzle extension (20 in.) of V 2 - or 
%-in. bore. The firing controls were actuated 
by one foot pedal which accomplished the fol¬ 
lowing in sequence. 

1. Actuation of the E20 igniter in the muzzle 
of the dummy gun tube, sending air and gaso¬ 
line through an atomizer nozzle to spray around 
dual high-tension spark gaps in the ignition 
chamber, forming a burning blowtorch through 
which the flame gun fires. 

2. Operation of the E20 flame gun, indirectly 
opening the internal main fuel valve and simul¬ 
taneously coating the ejected thickened fuel 
with unthickened gasoline or secondary fuel. 






no 


MECHANIZED FLAME THROWERS 


The E20 foot-pedal control permitted essenti¬ 
ally independent operation of the igniter. 

The gun elevated (—15 to +45 degrees) by 
handwheel also geared to the 75-mm rifle, and 
traversed with the turret.^ 


5-* E7-7 FLAME THROWER IN M5A1 TANK 
Introduction 

The development of the E7-7 mechanized 
flame thrower for the M5A1 light tank was 
initiated in January 1943 by the Standard Oil 
Development Co. under Contract OEMsr-390. 
The general objectives of the project included 
the design and construction of a practical modi- 
Aed turret-basket flame-thrower unit of long 
range, complete for ready installation in a 
standard light tank.^® 

The development was an outgrowth of the 
work previously done on the design of Models 
A, C, D, and Q flame throwers (see Sections 5.2 
and 5.3). Model Q had been successfully demon¬ 
strated in January 1943 as part of a trailer- 
model pilot device, and extensive tests of the 
system resulted in the decision that a similar 
unit be mounted for service tests in an M5A1 
tank. The design was further refined to modify 
the M5A1 turret and turret-basket assembly, 
so as to permit the installation of the E7 
(Model Q) gun and all auxiliary fuel and pro¬ 
pellant gas equipment within the basket. Four 
complete units were ultimately constructed and 
delivered to the theater of operations. 


Description 

Carrier. The E7-7 flame thrower was mounted 
in the M5A1 tank, which weighed 31,000 lb 
exclusive of crew, armament, and stowage. 
Modification for the flame gun weighed 2,650 
lb, including fuel. The usual conical turret 
basket of the M5A1 tank was replaced by a 
cylindrical basket to provide maximum capacity 
for fuel tanks and air cylinders (Figure 8). 
Hull stowage was slightly modified and reduced 
to accommodate this wider base basket, and 
normal turret equipment was modified or re¬ 


arranged to accommodate the flame-thrower 
equipment. The periscopes in the turret roof 
were relocated for convenience of turret and 
gun operation by the single turret occupant. 



Figure 8. Turret-basket assembly for E7-7 flame 
thrower in M5A1 light tank. 


Additional tank armament consisted of three 
.30-caliber machine guns and one .45-caliber 
sub-machine gun. The hydraulic-power traverse 
assembly was shifted to the rear turret shelf, 
displacing the radio, which was moved to the 
right hull sponson.-^ 

Propellant System. Compressed air, nitrogen, 
or inert gas could be used as propellants. The 
compressed gas was stored in 21 interconnected 
high-pressure gas cylinders under a pressure of 
2,000 psi for expulsion of the main fuel, and 2 
interconnected cylinders for expulsion of sec¬ 
ondary fuel (Figure 9). Automatic pressure 
regulators provided a working pressure of 340 
to 380 psi over the primary and 400 to 440 psi 
over the secondary fuel. Gas under 70 psi was 
used in the atomizer nozzles of the igniter. 

Fuel System. The primary fuel consistency 
recommended was approximately 400 g Gard¬ 
ner, corresponding to 7 per cent Napalm-gaso¬ 
line gel. It was carried in five drums connected 
in series, having a total net fuel capacity of 
107 gal, which was sufficient for about 45 sec 
firing time at 2.4 gal per sec. The resulting 
fuel holdup in the tanks was about 3 to 5 gal. 

The secondary fuel or unthickened gasoline 
was used to enhance the degree of ignition of 
the fuel rod. It was supplied under 400 to 440 
psi pressure at a rate of approximately 200 ml 






E7-7 FLAME THROWER IN M5A1 TANK 


111 


per sec from a single 3-gal container capable of 
56 sec of operation. The supply of secondary 
fuel was controlled by a valve synchronized with 
the main valve. The ratio of primary to sec¬ 
ondary fuel was approximately 19/1. 

E7 Gun. The E7 gun (see Section 5.3) which 
replaced the normal 37-mm gun of the tank 


by sparking an atomized spray of gasoline.^*^ An 
atomizer nozzle supplied with air at 70 psi and 
gasoline at 5 psi directed a cone of atomized 
gasoline down an 11-in. section of 4-in. pipe, 
which served as the igniter shield. Two inde¬ 
pendent ignition systems, each consisting of a 
high-tension spark gap, 12,000 volts alternating 


AIR 

28 


AIR ' 


J 

AIR 

H 

AIR 

r 

AIR 

24 


23 

19 

9 , 


MAIN HIGH PRESSURE 
AIR GAGE 0-3000 PSI 


MAIN FUEL 
PRESSURE 
GAGE 

0-1000 PSI 

o 


MAIN HIGH PRESSURE 
AIR SYSTEM RELIEF 
VALVE SET AT 2500 PSI 


n 

lAIR 

34 

AIR 1 
J35 

[1 


HIGH PRESSURE 
SECONDARY FUEL 
AIR CHECK VALVE 

AIR 

SECONDARY FUEL 
HIGH PRESSURE 
AIR RELIEF VALVE 
SET AT 2500 PSI 


FUEL FILLING INLET 



ATOMIZER GASOLINE 
STRAINER 

ATOMIZER CONTROL VALVE 
TRUNNION ELBOWS 


LOW PRESSURE 
SECONDARY FUEL 
AIR CHECK VALVE 


FLEXIBLE CONNECTORS 


Figure 9. Flow plan E7-7 flame-thrower system. 


was mounted at the top of the tank, in a turret 
which could be traversed, manually or by power, 
through 360 degrees. The gun could be de¬ 
pressed through 10 degrees, or elevated through 
30 degrees, from the horizontal. It was mounted 
in a simulated 75-mm howitzer muzzle, from 
which the ignited fuel was fired. A .30-caliber 
machine gun was mounted coaxially with the 
flame gun, and the front of the turret included 
a special large armored shield. 

Ignition System. Ignition was accomplished 


current, actuated by a spark coil operated from 
the 12-volt tank storage battery, were mounted 
in the igniter shield in such a way that the 
spark points protruded inside the boundaries 
of the spray cone. 

Performance 

Testing of the prototype in November 1943 
resulted in the decision to build three additional 
units as pilot models for training. The proto- 























































































































































































112 


MECHANIZED FLAME THROWERS 


type underwent additional tests by the Chemical 
Warfare Service-*^ and the Armored Board.-^ 
The latter recommended armoring of all four 
units to make them battleworthy, but to discon¬ 
tinue production because of obsolescence of the 
M5 tank. Operational tests of the battleworthy 
units-- revealed no weaknesses. An operational 
and maintenance manual was issued,and the 
four units, together with one E8 servicing unit, 
were sent to a theater of operations. 

Field tests of the prototype unit, using 7 per 
cent Napalm gasoline, showed a center-of-de- 
posit range of 105 to 115 yd at 10 degrees ele¬ 
vation and 120 to 130 yd at 20 degrees elevation, 
with a 5 to 10 mph tail wind (Figure 10). 



Figure 10. E7-7 mechanized flame thrower firing 
thickened fuel (8% Napalm) at embrasure, 
range 60 yd. 


Liquid kerosene could be projected 30 to 40 yd 
at 0 to 10 degrees elevation and with a 0 to 10 
mph tail wind (Figure 11). The range data on 
thickened fuels were generally confirmed in a 
series of tests by several groups. 

Operational Use 

The F7-7 saw action on Luzon. The first mis¬ 
sion was unsuccessful because of the terrain; 
the target was too far below the line of fire at 
maximum gun depression.-^- On a subsequent 
mission, definite targets were not apparent, but 
the approximate position of strong points was 
known. Bursts of 3 sec were fired onto the op¬ 
posite ridge until the flame-thrower tanks were 
emptied. Fight of the enemy were flushed out by 
the fire and killed by infantry, as a result of 
which enemy resistance was broken. An in¬ 
fantry attack followed, and the position was 



Figure 11. E7-7 mechanized flame thrower firing 
unthickened fuel (kerosene). Note intense flame 
and heavy smoke. 


taken, six fatally burned men being found at a 
heavy gun emplacement. Later official figures 
indicated that the combined flame thrower-in¬ 
fantry operation accounted for 56 enemy troops. 

During one week of heavy rains the ignition 
system of each unit was checked daily; no 
ignition failures were encountered. Other ac¬ 
tions are given in some detail in a separate 
report.^^ 

No troubles were encountered from faulty 
ignition or fuel instability. To minimize deposi¬ 
tion of fuel on the tank, rapid release of the 
trigger controlling the fuel valve and proper 
use of air blowdown were found essential. Oc¬ 
casional leaks were encountered in safety relief 
valves, around the ends of high-pressure hose, 
and around valve stems, none incapable of being 
readily repaired. Two spark-plug porcelain in¬ 
sulators were cracked. The sighting vane was 
made more rigid. One rubber O ring in a gun 
operating pilot valve required replacement due 
to slight wear. 

As to the overall adequacy of the flame¬ 
thrower installation in the tank, it was reported 
that, with all the equipment recommended, 
there was not sufficient room for the turret 
gunner, and that vision from inside the tank 
was poor. Other reported weaknesses were spe¬ 
cific to the tank itself. 

5- NAVY MARK I UNIT WITH E7 
FLAME THROWER 

Introduction 

Following demonstrations of Model Q to the 
Navy in December 1943 and January 1944, the 
Navy Department Bureau of Ordnance ordered 





NAVY MARK I UNIT WITH E7 FLAME THROWER 


113 


limited procurement of a flame thrower similar 
in design to Model Q to be constructed by M. W. 
Kellogg Co., with Standard Oil Development 
Co. under Contract OEMsr-390 contributing to 
basic design, necessary development, inspection, 
and testing.-^ These units, designated U.S. Navy 
Mark I, were to be complete with armor protec¬ 
tion suitable for crane loading ashore or afloat 
on LCVP or LCM landing boats. 

Twenty-one U.S. Navy Mark I units and ten 
additional pressure-vessel assemblies as spares 
or for use in series operation were constructed. 
In addition to acting as consultants during the 
construction, the Standard Oil Development Co. 
also trained Navy personnel and assisted in 
preparing operating and maintenance manuals-^’ 
as well as instructional movies. 


Description^ 

Introduction. Protected by front and side 
armor plate, the U.S. Navy Mark I flame 
thrower (Figure 12) was a compact unit com¬ 
prising an E7 flame gun and a pressure-vessel 
system carrying 200 gal of fuel with the neces¬ 
sary propellant air, nitrogen, or inert gas. The 
unit was designed primarily to operate with 
Napalm-thickened gasoline fuels, although liq¬ 
uid, unthickened fuels could be employed. Main 
fuel was coated with secondary fuel (motor 
gasoline) in the flame gun, prior to ejection 
through a cylindrical ignition chamber sur¬ 
rounding the gun nozzle (Figure 13). 

Propellant Systein. Propellant air, nitrogen, 
or inert gas at 2,000 psig was carried in seven 
standard cvlinders. 10.5 cu ft total capacity, 
bracketed horizontally in parallel close under 
the main fuel container. These cvlinders dis¬ 
charged to the rear through a pipe manifold 
into the adjustable automatic main pressure 
regulator which fed propellant gas to the main 
fuel container and the atomizer (igniter) fuel 
tank, and provided flame gun actuating and 
atomizer air to corresponding operating con¬ 
trols. Gas directly from the storage cylinders 
was also directed through a separate pressure 
regulator as propellant for secondary fuel. Pro¬ 
pellant gas was charged through a connection 
on the discharge manifold. Spring-loaded safety 


relief valves protected (1) the high-pressure, 
(2) main fuel, and (3) secondary fuel systems. 
The propellant gas cylinders were protected by 
vertical front and side armor plate. 

Fuel System. The main fuel system included a 
220-gal gross capacity, vertical, cylindrical, steel 
container with ellipsoidal heads, provided with 
a propellant air inlet at the top, a central ver¬ 
tical fuel discharge pipe, an overflow vent line. 



Figure 12. Rear view of U.S. Navy Mark I flame 
thrower. 


and a flanged top inlet for use in tandem with 
a second unit. The fuel discharge pipe extended 
internally from the bottom head through the 
top to feed and support the flame gun. The over¬ 
flow vent extended into the top sufficiently to 
create a 20-gal void space for expansion when 
the container was filled through a valved con¬ 
nection in the fuel discharge pipe above the 
vessel. A frangible rupture disk which burst at 
600 psig was installed in a safety blowoff con¬ 
nection in the propellant air inlet line. A semi¬ 
circular platform was built around the rear wall 
of the container as standing support for the 












114 


MECHANIZED FLAME THROWERS 



Figure 13. Flow diagram of U.S. Navy Mark I flame thrower. 


AJLflJLaJ 




















































































NAVY MARK I UNIT WITH E7 FLAME THROWER 


115 


gunner. A vertical front and side armor plate 
was bolted around the vessel for protection of 
the container and the operator. 

Secondary fuel was carried in a 3-gal vertical, 
cylindrical container mounted at the right of 
the main fuel container. Propellant gas at 500 
to 550 psig entered the top of the vessel. Sec¬ 
ondary fuel was ejected through a bottom dis¬ 
charge pipe to the forward end of the dual main 
control valve on the flame gun. The secondary 
fuel container was charged through a plugged 
top connection leading to a valved vent. An 
emergency propellant line extended from the 
main pressure regulator discharge through an 
air-check valve to the secondary fuel container 
top inlet, assuring positive flow of secondary 
fuel to the gun in case the secondary fuel regu¬ 
lator discharge pressure was inadvertently set 
below the main fuel operating pressure. 

E7 Gun. The E7 gun (see Section 5.3) was 
mounted on the vertical discharge pipe directly 
over the main fuel container. 

Ignition System. The U.S. Navy Mark I igni¬ 
tion system included facilities for producing an 
air-atomized spray of gasoline around dual 
spark gaps in the ignition chamber through 
which main fuel was ejected from the flame 
gun. Atomizer fuel (V^-gal motor gasoline) was 
stored in a vertical, cylindrical container to the 
left of the main fuel tank. Propellant gas at 
4 to 7 psig entered the top of the container 
from the atomizer-fuel pressure regulator tak¬ 
ing part of the discharge from the main pres¬ 
sure regulator. Atomizer fuel was discharged 
from the bottom of the container through the 
dual atomizer control valve to the atomizer 
nozzle. The container was filled through a top 
plugged connection. Air at 60 to 65 psig to the 
atomizer nozzle was supplied through a separate 
regulator also fed by the main pressure regula¬ 
tor. This air passed through the dual atomizer 
control valve to the atomizer nozzle simultane¬ 
ously with atomizer fuel. Twelve volts direct 
current for the ignition system was supplied 
from two 6-volt storage batteries, mounted one 
on each side of the main fuel container over 
the bank of propellant gas cylinders. This low- 
tension current was led through the left firing- 
handle trigger switch to dual special splash- 
proof coil boxes mounted behind the gun shield. 


From each coil box, 12,000 volts alternating 
current was delivered to 1 of two special igniter 
spark plugs mounted parallel to the flame-gun 
nozzle in the ignition chamber. Here dual 
sparks were generated to grounding electrodes 
in the chamber wall simultaneously with ejec¬ 
tion of a spray of gasoline from the atomizer 
nozzle. Sparking of either igniter plug alone 
was capable of igniting the atomizer gasoline, 
the dual high-tension circuit being employed as 
an ignition safety factor. The ignition cham¬ 
ber consisted of a 12-in. extension of a cylin¬ 
drical tube surrounding the flame-gun nozzle 
and forward of it. The ignition chamber was 
bolted at the rear end to a vertical ballistic plate 
through which the dual spark plugs were 
screwed. The E7 nozzle projected approxi¬ 
mately 2 in. through this plate and ejected con¬ 
centrically through the ignition chamber. The 
atomizer nozzle was mounted to the rear of the 
ballistic plate and ejected through it into the 
ignition chamber. The ignition chamber was re¬ 
movable for servicing or replacing spark plugs. 
Bolted to the ballistic plate and the forward 
gun-body flange, a cylindrical nozzle cover to 
the rear of the plate and ignition chamber was 
split horizontally and encased the ignition lead 
wires, the spark plug rear terminals, the atom¬ 
izer nozzle feed lines and the atomizer nozzle. 
These could be serviced by removal of the top 
half of the nozzle cover. Twenty holes drilled 
into the bottom half of the nozzle cover sup¬ 
plied necessary secondary air drawn into the 
ignition chamber by the jet action of the atom¬ 
izer spray passing through a hole in the top 
half of the ballistic plate. 

Units in Tandem. To increase fuel capacity 
and firing time for waterborne assault where 
sufficient landing boat cargo space was avail¬ 
able, it was originally planned to connect 
two Mark I units in tandem, back to back, using 
the flame gun only on the forward unit. Tests 
showed satisfactory tandem operation with the 
propellant gas, main fuel, and secondary fuel 
systems connected in series through flexible 
hoses, and controlled by the pressure regulators 
on the rear unit. The ignition system and igniter 
fuel supply on the forward unit alone were 
adequate in this case. Main fuel flowed from 
the rear unit fuel-charging inlet to the special 




116 


MECHANIZED FLAME THROWERS 


top inlet on the forward main fuel container. 
Inasmuch as the U.S. Navy Mark I units were 
transported in combat in LVT-4 amphibious 
tanks of limited cargo capacity, series opera¬ 
tion of two units in tandem was not employed 
in battle. 


Performance 

One of the twenty-one units was assigned 
with Navy personnel for extended testing by 
the Chemical Warfare Service, Technical Divi¬ 
sion, at Edgewood Arsenal. Navy personnel ac¬ 
companied production units to the West Coast 
for a limited period of additional training and 
testing. This was continued at Pearl Harbor, 
where a U.S. Navy Mark I unit was installed in 
an obsolete M3 medium tank during further 
flame-thrower studies. Meanwhile, practice 
landings with a Mark I unit mounted in an 
LCVP indicated the need for employing a car¬ 
rier which would not immobilize the flame 
thrower after reaching the beach. 

Typical range data for the unit are given 
below. 

Firing 8 per cent Napalm-thickened gasoline 

10° elevation 20° elevation 


Nil wind 

100 yd 

110 yd 

5-niph tail wind 

110 

123 

10-mph tail wind 

120 

135 

5-mph cross wind 

75 

81 

10-mph cross wind 

56 

60 


Firing liquid fuel (kerosene) 

0 to 10-mph tail wind 30 to 40 yd (extreme range) 

0 to 10° elevation 

Six U.S. Navy Mark I flame throwers were 
effectively employed in combat in the Palau 
operations on Peleliu Island from September 15 
to November 26, 1944.-" Carried in the open 
cargo compartments of LVT-4 lightly armored 
amphibious tractors, the units were used suc¬ 
cessfully during flame attacks against large 
Japanese pillboxes, caves, foxholes, hillsides, 
ammunition and food dumps, and emplacement 
areas which rendered conventional attack costly 
(Figure 14). At a cost of only 11 casualties to 
the operating personnel, over 300 entrenched 
enemy troops were killed directly or indirectly 
because of the flame-thrower action. Fifty loads 
of fuel were fired, and a total of 23 LVT-4 trac¬ 
tors were employed to maintain operation of the 


six Mark I units until the island was secured. 
The units proved rugged in combat and were 
still operable at the end of the campaign. 
Although employed effectively, the LVT-4 car¬ 
riers proved mechanically deficient and offered 
insufficient protection to operating personnel. 

The U.S. Navy Mark I demonstrated beyond 
reasonable question the important tactical value 



Figure 14. Action of U.S. Navy Mark I flame 
thrower mounted in LVT-4 amphibious tractor 
on Peleliu Island, October 1944. 


of a large-capacity, long-range flame thrower in 
combat, emphasizing the need for improved mo¬ 
bility and adequate protection of operating per¬ 
sonnel in battle. In combat, the unit proved 
most effective in reducing enemy emplacements 
and flushing out occupants where conventional 
weapons, aerial bombing, or artillery fire failed 
to minimize personnel casualties during assault 
or mopping-up operations. Use of up to 9 per 
cent Napalm-thickened fuel effected ammuni¬ 
tion explosions inside enemy emplacements and 
permitted accurate penetration of small em¬ 
brasures from 80 yd range with the i/i-in- noz¬ 
zle employed. 

5 E14-7R2 FLAME THROWER IN LVT-Al 

AMPHIBIOUS TANK 

Introduction 

The development of the E14-7R2 was ini¬ 
tiated by the Chemical Warfare Service, who in 
January 1944 requested that a flame-thrower in- 



E14-7R2 FLAME THROWER IN AMPHIBIOUS TANK 


117 


stallation in an LVT-Al amphibious tank be 
built by the Lima Locomotive Works, with Stand¬ 
ard Oil Development Co. under Contract OEMsr- 
390 acting as engineering consultants for CWS- 
Technical. The E14-7R2 prototype unit, desig¬ 
nated E7-LVT-Al,-s when tested, was basically 
satisfactory as a flame thrower, but with full 
standard LVT-Al combat stowage was some¬ 
what overweight and bow-heavy while water¬ 
borne in moderate surfs.-^ To overcome this 
difficulty, several modifications were made and 
the resulting unit, E14-7R2, was built by the 
M, W. Kellogg Co. Basic corrections included 
weight reduction of the flame-thrower installa¬ 
tion wherever possible, with movement of the 
pressure vessels downward and towards the 
rear of the vehicle.^®- 

In addition to the furnishing of basic design 
and development work, assistance was given in 
preliminary testing, establishing inspection 
procedure, instructing Armored Force person¬ 
nel, and preparing informational movies and 
manuals. 


Description"’^"’"" 

Carrier. The E14-7R2 essentially duplicated 
the standard LVT-Al amphibious tank with the 
exception of a few modifications. The 37-mm 
rifle, gun mount, and counterweight were re¬ 
placed by the E7R2 flame gun and integral trun¬ 
nion mounting, dummy gun tube, and special 
counterweight. The .30-caliber coaxial machine 
gun was retained, but the coaxial sighting tele¬ 
scope was eliminated. All gun gyro stabilizer 
equipment was removed. 

It was necessary to broaden slightly the tur¬ 
ret front in order to accommodate both the 
flame gun and the coaxial machine gun. The 
turret power-traverse control was changed 
from the standard rotatable pistol grip to a 
left foot pedal for the flame gunner. Also, me¬ 
chanical stops were installed to prevent turret 
traverse beyond 120 degrees to the right or 
left of the vehicle longitudinal center line. This 
prevented any possibility of firing the flame 
gun over the heads of the two rear scarf gun¬ 
ners. Other minor changes were made in the 
turret (Figure 15). 


Similarly, the hull had to be modified to ac¬ 
commodate the flame-thrower fuel and pressure 
system. In addition, three 10-lb CO 2 cylinders 
were installed in the right side of the engine 
room. These were manifolded to discharge 
horns distributed through the cargo compart- 


P7P'> ATnAy^l7FR FllFL 



' CONTAINERS CONTAINER 


Figure 15. E14-7R2 flame-thrower installation 

showing position of gun and containers. 

ment and bilges, and were provided with inter¬ 
nal and external pulls to save the equipment in 
case of fire accompanying relatively minor 
damage. 

Propellant System. Stored at 2,000 psig pres¬ 
sure in the cargo compartment, 8.2 cu ft total 
of propellant air, nitrogen, or inert gas was 
carried in four interconnected horizontal cyl¬ 
inders of equal capacity, located in pairs against 
each side bulkhead. This stored pressure was 
directed through adjustable, automatic pres¬ 
sure regulators (1) to propel main fuel from 
the containers through the flame gun, (2) to 
propel secondary fuel through the gun to coat 
the main fuel prior to ejection, (3) to propel 
atomizer (igniter) fuel through the atomizer 
nozzle into the dummy gun-tube ignition cham¬ 
ber, (4) to provide atomizer air, mixing with 
atomizer fuel in the nozzle as described in 3, 
and (5) to provide flame gun actuating air to 
open the E7R2 main fuel valve. 

The main regulator supplied controlled 375 
to 400 psig pressure into the top of the right 
main fuel container and also fed this pressure 
to individual regulators as described in 3, 4, 
and 5. Secondary fuel pressure was controlled 
through a separate regulator at 500 to 550 
psig. 

Fuel System. Main fuel for the flame gun was 

















118 


MECHANIZED FLAME THROWERS 



12 V - 0 C 




















































































































E14-7R2 FLAME THROWER IN AMPHIBIOUS TANK 


119 


carried in two 105-gal vertical, cylindrical pres¬ 
sure vessels connected in series in the cargo 
compartment (Figure 16). These containers 
were placed symmetrically in the hull to main¬ 
tain lateral trim of the vehicle afloat, and were 
limited to the indicated capacity because of 
vehicle weight limitations for acceptable sta¬ 
bility while waterborne. The containers were 
piped to the flame gun in the turret through 
a special rotary joint in the basket floor. 

Fuel was charged to this system through an 
external armor-protected inlet in the right rear 
turret wall, flowing in reverse through the fuel 
piping in the turret into the hull containers in 
series. When these containers were full, fuel 
overflowed outside through a vent pipe over the 
right fender, connected by a temporary hose to 
a waste receiver on the ground. 

Secondary fuel, ordinary motor gasoline, was 
carried in a 7.5-gal vertical cylinder in the left 
rear cargo compartment. This fuel, propelled at 
500 to 550 psig pressure, flowed through the 
E7R2 main control valve into the flame gun 
when the main fuel valve in the weapon was 
actuated. 

E7R2 Gun. A description of the E7R2 was 
given in Section 5.3. Although the flame gun 
does not differ much from the E7, it had to 
be thoroughly waterproofed for amphibious 
use. 

Ignition System. Propelled by 5 to 10 psig 
pressure supplied in series through the main 
air, atomizer air, and atomizer fuel regulators, 
1/2 gal of atomizer fuel (ordinary motor gaso¬ 
line) was stored in a vertical cylindrical con¬ 
tainer in the right rear cargo compartment. 
When the ignition pedal was pressed by the 
flame gunner, the fuel flowed through the atom¬ 
izer valve into the atomizer nozzle discharging 
into the ignition chamber at the forward end 
of the dummy gun tube. In the atomizer nozzle, 
the fuel was mixed with air under pressure 
(regulated to 70 to 80 psig, also controlled 
through the dual atomizer valve) and expelled 
as a finely atomized spray around dual spark 
gaps in the ignition chamber. 

Simultaneously, the ignition pedal closed an 
electrical switch which sent 12-v direct cur¬ 
rent, obtained from the vehicle storage battery, 
to two special coil boxes located under the for¬ 


ward turret roof. Each coil box independently 
fed 12,000 V interrupted potential to one of 
two special spark plugs placed in the ignition 
chamber at the muzzle end of the dummy gun 
tube. The air-atomized gasoline spray was re¬ 
leased into the ignition chamber where it sur¬ 
rounded and was ignited by the dual sparks 
emitted by the spark plugs to grounding elec¬ 
trodes on the dummy tube walls. Sparking of 
either spark plug alone was sufficient to ignite 
the atomizer spray. As long as the ignition 
pedal was fully depressed, the resulting flame 
persisted as a blowtorch through which the 
main fuel rod, coated with secondary fuel, had 
to pass. 


Performance 

As a large-capacity, long-range, main-arma¬ 
ment, mechanized flame thrower, the E14-7R2 
unit was designed principally to fire gasoline 
fuels thickened with up to 10 per cent by weight 
of Napalm. Fuel thickened with 6 to 8 per cent 
Napalm was generally employed for optimum 
combined performance and serviceability (Fig¬ 
ure 17). Liquid, unthickened fuel could also be 



Figure 17. E14-7R2 firing 8% Napalm-thickened 
fuel using 5° elevation, range 80 yd. 


used, although at very appreciable sacrifice in 
range, aimability, and burning time on the tar¬ 
get. With liquid unthickened fuels, about one 
pint residual remained after each prolonged 
shot in the E7R2 gun nozzle downstream of the 
internal main fuel valve. 

The unit was capable of ejecting a total of 
190 to 195 gal of thickened fuel at approxi¬ 
mately 2.4 gal per sec for 80 sec with Vo-in. 








120 


MECHANIZED FLAME THROWERS 


bore nozzle, or 4.8 gal per sec for a total of 40 
sec with %-in. nozzle. These nozzles were inter¬ 
changeable between missions. 

Either rapid (V 2 to 1 sec bursts) or pro¬ 
longed fire, ignited or unignited at the will of 
the gunner, was permitted with the E7R2 gun. 
Typical average ranges measured from the gun 
to the center of the ground pattern on level 
terrain were as follows. 

Approximate range in yards to center of ground 
deposit 

2 -in. nozzle f-in. nozzle 

Nil wind 

10° Elevation 95 105 

20° Elevation 105 125 


5-mph wind 

Tail 

Cross 

Tail 

Cross 

10° Elevation 

105 

75 

115 

85 

20° Elevation 

115 

80 

140 

95 

10-mph wind 

10° Elevation 

110 

60 

125 

65 

20° Elevation 

125 

60 

150 

75 


The end of World War II prevented the use 
of the E14-7R2 in actual combat, but ten units 
were completed. 


- ‘ M5-4 (E12-7R1) FLAME THROWER IN 

M4A1 AND M4A3 MEDIUM TANK 

Introduction 

The development of the E12-7R1 mechanized 
flame thrower for the M4A1 medium tank was 
initiated in August 1944 by Standard Oil De¬ 
velopment Company under Contract OEMsr- 
390. The replacement of the main armament in 
the M5A1 light tank by a large-capacity flame 
thrower had resulted in the construction of four 
Model E7-7 mechanized flame throwers, which 
were delivered to the theater of operations and 
successfully used in the Pacific Theater (see 
Section 5.4). However, the basic vehicle of the 
E7-7 lacked sufficient power and sturdiness, and 
in the spring of 1944 NDRC was convinced 
of the need for mechanized flame throwers of 
still higher range and capacity, mounted in me¬ 
dium tanks. By summer, M4A1 tanks had been 
secured for two new projects, E13-13 and 
E13R1-13R2. Military interest in mechanized 
flame throwers was growing so rapidly during 
this period that by autumn of 1944 the imme¬ 


diate production of 20 flame throwers in M4A1 
tanks was requested. Since both the above proj¬ 
ects involved untried design principles and an 
untested gun, it was considered unwise to go 
into production on them. The present project 
was accordingly launched, the design to be 
based on the battle-tested E7 gun and on the 
use of conventional, air-pressurized fuel bottles 
in series. 

The general objectives of the project, there¬ 
fore, included the development of a main-arma¬ 
ment mechanized flame thrower for medium 
tanks which would permit a large fuel capacity, 
a high rate of fuel discharge, and a long effec¬ 
tive range, in excess of 100 yd. With these ob¬ 
jectives in view, the final design incorporated 
a modified Q(E7) flame gun, the principal flow 
and operating features of the system being quite 
similar to those of the E7-7 (see Section 5.4). 
Principal differences consisted in the design of 
specific component parts to adapt the flame 
thrower to an M4A1 or M4A3 medium tank. 


5.7.2 DescriptioiP’ 

Carrier. The E12-7R1 flame thrower was 
mounted in the M4A1 or M4A3 tank. The turret 
basket was rebuilt and shortened by 7 in. to 
accommodate the flame-thrower system. Tur¬ 
ret stowage was modified to include one main 
fuel and three auxiliary pressure containers in 
the left half of the basket along with operating 
controls for the flame gun, eliminating the can¬ 
noneer (gun loader) and retaining the tank 
commander and gunner in their original turret 
positions. 

The 75-mm cannon, gun mount, and counter¬ 
weight were replaced by the E7R1 flame gun 
and dummy 75-mm gun tube, rotor mount, and 
special counterweight. All M4A1 or M4A3 
armament other than the 75-mm cannon was 
retained. Externally, the flame-thrower tank 
had the appearance of a standard M4A1 or 
M4A3 medium tank with 75-mm gun. 

Where the main generator was originally 
placed on the hull floor near the driver, it was 
replaced by a standard generator mounted over 
the driveshaft. The batteries and generator 
regulator were moved from the hull floor to the 



M5-4 (E12-7R1) FLAME THROWER IN MEDIUM TANK 


121 


left sponson, the hull was rewired, and the other 
hull and sponson stowage was modified to ac¬ 
commodate flame-thrower fuel and air-pressure 
containers. 

The vehicle, as modified, was thus equipped 
with the following armament: one flame 
thrower, mechanized, E12-7R1, two .30-caliber 
machine guns (one gun coaxial with the flame 
gun in the turret, one bow gun operated by the 
assistant driver), one .50-caliber A A machine 
gun, external mount on turret. The total operat¬ 
ing crew consisted of four men. 

Propellant System. Compressed air was used 
as propellant, and was stored in six high-pres¬ 
sure air cylinders (Figure 18). Two of these, 
placed in the right and left sponsons, were con¬ 
nected to four smaller cylinders located around 
the hull fuel containers. The air used for actuat¬ 
ing the flame gun was carried in a separate con¬ 
tainer in the turret basket. 

The air system can be tabulated as follows. 


Total number of cylinders 
In hull, to expel main fuel 
In turret basket, auxiliary 
and gun operating air 
Total capacity 
Starting pressure 
Final pressure, after fir¬ 
ing main fuel load 


7 

6 (total 10.1 cu ft) 

1 (2.7cuft) 

12.8 cu ft 
2,200 psi 

Approx 500 psi in hull 
Approx 1,400 psi in basket 


Fuel System. The recommended primary fuel 
was 7 per cent Napalm-gasoline gel of approxi¬ 
mately 400 g Gardner consistency. It was car¬ 
ried in two horizontal, internally baffled main 
fuel containers accommodated in the hull, and 
in a third vertical main fuel container located 
in the turret basket (Figure 19). All three fuel 
containers were connected in series and had a 
combined capacity of 315 gal. The static pres¬ 
sure setting of the high-pressure regulator in 
the air line to the fuel containers was 375 to 
400 psi, producing an operating pressure at the 
gun of 325 to 350 psi. 

The secondary fuel, unthickened gasoline, 
was carried in one 15-gal container located in 
the turret basket and was supplied under ap¬ 
proximately 500 psi pressure at a rate of 150 to 
300 ml per sec. The supply of secondary fuel 
was controlled by a pedal valve synchronized 
with the main fuel valve. 

E7R1 Gun. The F7R1, described in Section 


5.4, had a 360-degree traverse and an elevation 
of from —12 to +25 degrees. 

Ignition System. Gasoline from the 2-gal 
atomizer fuel container passed at 7 to 8 psi 



( HORIZONTAL, BAFFLED) 
t VESSEL IN BASKET 
(VERTICAL) 

(SERIES FLOW) 

Figure 18. Simplified flow plan of M5-4 (E12- 

7R1) mechanized flame thrower. 

through the atomizer nozzle installed near the 
end of the dummy 75-mm gun tube, was mixed 
and atomized with air at 70 to 80 psi, and was 
ignited by dual spark plugs. This ignited mix¬ 
ture, discharged at about 1.5 to 3.0 ml per sec, 
in turn ignited the main fuel rod leaving the 
flame gun. Current for the two high-tension 
spark plugs was drawn from one 12-volt storage 
battery of the vehicle. 

E12R1-7R1 Modification. The F12-7R1 flame 
thrower, simplified by certain modifications, 
constituted the F12R1-7R1 flame thrower. 

In converting the fuel and air systems, the 
basket primary fuel tank was omitted, thereby 
reducing the fuel storage capacity to 235 gal 
gross, 210 gal net. The capacity of the secondary 
fuel tank was reduced from 15 to 11.5 gal. The 
number of air cylinders was reduced to two in 
the hull and 1 in the basket, with a total ca¬ 
pacity of approximately 10 cu ft. The ignition 






























122 


MECHANIZED FLAME THROWERS 


gasoline container was reduced in capacity to 
2 gal. 



Figure 19. Schematic flow diagram of the main 
fuel system of M5-4 (E12-7R1) flame thrower. 


Performance'^'^’ 

Typical range data (center of ground de¬ 
posit) as obtained by the contractor when fir¬ 
ing 8 per cent Napalm-thickened gasoline (Fig¬ 
ure 20), is shown below in yards. 

Nil wind 10-degree elevation 20-degree elevation 


i-in. nozzle 

78 

95 

i-in. nozzle 

95 

105 

1-in. nozzle 

113 

140 

5-mph tail wind 
i-in. nozzle 

88 

106 

1-in. nozzle 

103 

121 

4 -in. nozzle 

125 

154 


A special CWS-NDRC Mechanized Flame- 
Thrower Evaluation Group set up at Edgewood 
Arsenal carried out exhaustive tests of the per¬ 
formance of the E12-7R1 flame thrower, and 
arrived at the conclusion that the mechanical 
functioning of the unit was substantially fault¬ 
less, except for the desirability of increasing 
the diameter of the refueling line and connec¬ 
tions to insure more rapid filling with thickened 



Figure 20. M.5-4 (E12-7R1) firing 8% Napalm- 
thickened fuel, range 65 yd. 


fuel.''^^ The group found the following center-of- 
deposit ranges with the E12-7R1 unit firing 
under various conditions at a 5-degree elevation 


and a head wind of 5 

to 10 mph: 


Fuel, g Gardner 

Nozzle, in. 

Range, yd 

230 

i 

89 

239 

i 

79 

400 

f 

75 

400 

,1 

74 

700 

1 

74 

700 

i 

65 


On the basis of a series of physiological tests 
in a typical pillbox, the group, in conjunction 
with the CWS Toxicological Laboratory, ar¬ 
rived at the conclusion that the optimum fuel 
consistency for use with the 'j4-in. nozzle of the 
E12-7R1 flame thrower would be one of 200 to 
250 g Gardner or 6 to 6.5 per cent Napalm, 
and that the maximum effective range for lethal 
conditions in the enclosure would be approxi¬ 
mately 80 yd, that is, considerably less than in¬ 
dicated by open field tests.The bunker tests 
were generally confirmed by dispersion target 
tests devised and carried out by the Evaluation 
Group. 


>« E8 FLAME THROWER IN M5A1 
LIGHT TANK 

Introduction 

The development of the E8 mechanized flame 
thrower mounted on the M5A1 light tank was 
initiated in January 1943 by C. F. Braun & 
Co. under OSRD Contract OEMsr-943. The gen¬ 
eral objectives of this project included the de¬ 
velopment of an easily installed, self-contained 
unit of large fuel-carrying capacity, incorporat¬ 
ing a flame gun of flexible design, and intended 











































E8 FLAME THROWER IN M5A1 LIGHT TANK 


123 


to discharge 3 to 5 gal of thickened fuel per 
sec to an effective range of approximately 200 
yd. Although pump propulsion was contem¬ 
plated, the final design provided for propulsion 
by means of compressed air carried in separate 
cylinders, and high fuel capacity was obtained 
at the cost of removing the turret, traversing 
mechanism, and all armament from the tank. 
Later, a machine gun was reinstalled in a small 
armored turret on the outside of the tank. 

Preliminary experimental work included 
comparative studies of propulsion methods by 
straight gas pressure from a vessel, by pump 
alone, and by pump with hydromatic accumu¬ 
lator, as well as investigations into pressure 
drops, nozzle shapes, jet forms, and trajectories. 


Description^*^’ 

Carrier. The E8 flame thrower was designed 
for installation in a modified M5 tank. In order 
to achieve a high fuel-carrying capacity, the 
turret and its traversing mechanism were re¬ 
moved. The engine compartment bulkhead and 
doors were left in place. A fireproof bulkhead 
was installed just behind the driver’s compart¬ 
ment. The tank roof between the two bulkheads 
was removed, the sidewalls were raised, and a 
new roof was installed on a level with the M5 
turret. The resulting silhouette was slightly 
shorter and about 40 per cent wider than the 
M5 turret. The flame gun was mounted in a 
small turret placed at the forward end of the 
new roof assembly. 

The flame-thrower equipment was assembled 
as a single unit and was attached to the roof. 
Thus it could be installed in the tank with lim¬ 
ited shop facilities. 

Propellant System. Compressed air at about 
2,000 psi was carried in four bottles, two in¬ 
stalled in the tank sponsons and two smaller 
ones mounted vertically alongside the fuel bot¬ 
tles. The total capacity of the bottles was about 
9 cu ft. The air bottles were divided into two 
groups, each of which was provided with a 
check valve. Thus the system was protected 
against total loss of air pressure, should any one 
of the bottles be punctured. A Grove regulator 
controlled the air pressure at 350 to 400 psi for 


ejection of fuel. Another small regulator pro¬ 
vided 100 to 150 psi air for valve operation. 

Fuel System. Fuel was carried in two bottles 
connected in series. Their total capacity was 
approximately 240 gal. The bottles were 
mounted vertically in the forward part of the 
flame-thrower compartment. They were rigidly 
tied together and were used as a base to which 
all other parts of the flame thrower were at¬ 
tached. As a result, the entire flame-thrower 
system could be lifted out of the M5A1 tank and 
operated independently or in another carrier. 

Fuel was admitted to the gun by the main 
valve, located downstream from the fuel bot¬ 
tles. This valve was opened by compressed air 
and was closed by a spring. The force to open 
or close the valve was nearly independent of 
the working pressure, thus allowing very rapid 
opening and closing. 

Gun. The gun contained a pintle valve oper¬ 
ated by fuel pressure and consisted of the 
following three principal elements: nozzle, re¬ 
tractor tube and tip, and barrel (Figure 21). 



Figure 21. Cutaway of Braun ejector nozzle 
showing pintle valve in open position. 

The nozzle and the conical retractor tip 
formed the nozzle pintle valve; the included 
angle of the retractor tip cone was slightly 
larger than that of the nozzle cone. The func¬ 
tion of the pintle valve was to ensure a sharp 
cutoff of fuel at the nozzle at the end of a shot, 
after the main fuel valve had closed. The pintle 
valve was operated by fuel pressure. Its back¬ 
ward motion was opposed by a spring which 
continually exerted a pressure less than the 160 
psi operating pressure on the upstream face of 
the valve. Thus, when the fuel pressure in the 
gun was greater than the spring pressure, the 
pintle valve was forced open; when the fuel 






















124 


MECHANIZED FLAME THROWERS 


pressure dropped to less than the spring pres¬ 
sure, the valve was closed by the spring. The 
pintle valve could be locked in the closed posi¬ 
tion by means of a manual screw feed provided 
for this purpose. 

The retractor tube served as a support for 
the retractor tip. It was supported and aligned 
near the nozzle by a short sleeve through which 
it was free to slide. The sleeve was held in po¬ 
sition by four symmetrically placed, thin, 
streamlined fins which extended between the 
sleeve and the gun barrel. A portion of the re¬ 
tractor tube served as a case for the pintle 
valve opposing spring. 

In the gun, fuel flowed in the annulus between 
the retractor tube and the gun barrel. 

Directly following the pintle valve was the 
convergent section of the nozzle. It was so de¬ 
signed that when the pintle was in the open 
position, the fuel would accelerate at a constant 
rate in passing through the section. Inter¬ 
changeable nozzles of %-in., and %-in. 

diameters were provided. Following the mini¬ 
mum cross section was a straight section six 
diameters long. Secondary fuel, gasoline, from 
a 71 / 2 -gal pressurized tank was introduced just 
upstream from the beginning of the straight 
section through an annular opening. 

Fuel was passed to the gun through a hollow 
swivel joint and hollow trunnions, allowing tra¬ 
verse and elevation of the gun. Traverse was 
limited to 180 degrees, frontal, by the turret 
construction. The gun could be elevated 25 de¬ 
grees and depressed 7 degrees from the hori¬ 
zontal. 

The gun was controlled by a single vertical 
lever, which was given a sidewise motion to 
traverse the gun; a forward or backward 
motion depressed or elevated the gun. A push¬ 
button in the lever handle fired the gun by 
admitting compressed air to the main fuel 
valve. 

Ignition System. The blowtorch principle 
was used for ignition. When starting cold, gaso¬ 
line was vaporized by means of an electric 
heater operated from the battery circuit of the 
tank. After the unit had warmed up, ignition 
gasoline was vaporized by heat from its own 
flame as it passed through a coil in the flame. 
The capacity of ignition gasoline storage was 


l/i gal, which was sufficient for 15 hours’ con¬ 
tinuous burning of the two torches used. 


Performance 

Woi’k on the E8 flame thrower was continued 
only to the point of constructing a prototype 
and demonstrating it at Edgewood Arsenal,^-- 
but no exhaustive performance tests were 
subsequently made. The demonstration at 
Edgewood suffered somewhat because of the 
excessively high consistency of the Napalm- 
gasoline gel used, 460 g Gardner, which resulted 
in imperfect ignition. Kerosene was used as sec¬ 
ondary fuel. 

Although the unit performed well, and was 
excellent with respect to fuel cutoff as well as 
the ease and rapidity of mounting and dis¬ 
mounting, no future development was under¬ 
taken, chiefly because of the obsolescence of the 
M5A1 model tank which was used as the 
carrier. 


> IMODEL 1-3 FLAME THROWER 

^ Introduction 

The development of the 1-3 mechanized flame 
thrower was initiated in October 1943 by Shell 
Development Co. under Contract OEMsr-916. 
The general objectives of this project included 
the design of a flame thrower incorporating a 
simple pintle valve design which would lend 
itself readily to adaptation to any particular 
vehicular mounting without major modification 
of the design. 

The original I-l gun design was a simplified 
adaptation of the E8 gun (see Section 5.8). 
involving elimination of the quick-acting valve 
mechanism of the latter, the pintle valve serv¬ 
ing as the main valve. Further simplification 
of the design resulted in the 1-2 model, which 
combined the nozzle and valve into a single 
angle valve and provided connection to the fuel 
line through a standard Unibolt ball joint. The 
final 1-3 design incorporated an improved 
method of mounting, including suitable trun¬ 
nion and swivel joints. Development of the 1-3 



MODEL 1-3 FLAME THROWER 


125 


gun never proceeded to the point of designing 
a complete production model, although several 
tests were run with a large fuel tank specially 
constructed for the purpose (Figure 22). 



Figure 22. Experimental Model 1-3 with 500-gal 
fuel tank. 


^ Description^^’ 

Carrier. Development did not proceed to the 
point of selecting the most suitable carrier for 
the system. 

Propulsion System. Compressed air was used 
for propulsion of the fuel, and was supplied at 
operating pressure from the compressed-air 
storage through a Grove regulator to the fuel 
tank, in which it was kept separated from the 
Napalm gel by a synthetic rubber bag dia¬ 
phragm. 

Fuel System. The system used in field tests 
of Model 1-3 consisted of a 500-gal tank em¬ 
ploying a synthetic rubber bag which served to 
transmit air pressure to the fuel (Figure 23). 
The synthetic rubber bag contained four longi¬ 
tudinal reinforcing straps of I4x2-in. steel at 
30 degrees from the vertical plane with welded- 
in studs to secure the bag to the upper part of 
the steel tank. Three dished steel plates built 
integral with the bag provided reinforcement 
covering the 2-in. discharge ports on the bot¬ 
tom of the tank. The air inlet to the bag was 
through a 2-in. molded flange in the top. In 
filling the tank with fuel, the bag diaphragm 
was filled with air to about 15 psi, and fuel was 
pumped into the steel tank through the bottom 
ports, the air being expelled from the inside of 



Figure 23. Diagrammatic sketch showing the 
action of synthetic rubber diaphragm. 

the bag through a bleeder valve. After charging 
the tank with fuel, the fuel inlet valve was 
closed, and air to fuel operating pressure was 
applied to the bag by means of the Grove regu¬ 
lator. 

Gmi Unit. The 1-3 gun, which was provided 
with a %-in. nozzle, had full 360-degree rota¬ 
tion, 43-degree elevation, and 15-degree depres¬ 
sion. The pintle valve was kept closed by air 
at the same pressure as in the main fuel tank, 
and firing of the gun was accomplished by re¬ 
leasing the air pressure through a three-way 
valve, the gel pressure itself opening the pintle 
valve (Fig. 24). At the end of firing, the release 



Figure 24. Model 1-3 flame-thrower nozzle show¬ 
ing pintle valve in open position. 


of the trigger readmitted air behind the pintle, 
shutting off discharge. 

Although provision was made for admission 
of secondary fuel, the jet showed satisfactory 
ignition with primary fuel alone under the not 
very severe conditions of test used. It is ex¬ 
pected that cold weather would have established 
the need for secondary fuel. 










































126 


MECHANIZED FLAME THROWERS 


Ignition System. The ignition system con¬ 
sisted of a 2 -gal gasoline tank on the left of the 
gun, and batteries and spark coil on the right. 
The gasoline was atomized with air from the 
air bottles and ignited by an automobile spark 
plug. 


Performance 

In field tests, the 1-3 gun showed excellent 
operating characteristics.^'^ With 8 per cent 
Napalm gels, maximum ranges of 135 to 150 yd 
to the center of deposit of the burning fuel were 
obtained with the %-m. nozzle; the correspond¬ 
ing ranges with 2.5 per cent Napalm were 35 to 
90 yd. The pintle valve, which was the only 
moving part, performed satisfactorily, and cut¬ 
off was rapid and clean. Fuel holdup in the 
tank was only 1 per cent of the 500-gal charge. 


5 E9 FLAME THROWER IN M5A1 
LIGHT TANK WITH FUEL TRAILER 

Introduction 

The development of the E9 mechanized flame 
thrower for the M5 light tank was initiated in 
April 1943 by Standard Oil Co. of Indiana un¬ 
der OSRD Contract OEMsr-1011. The general 
objectives of this project included attainment of 
greater effective range (approximately 200 yd) 
and the use of increased nozzle diameters 
(% in.) higher consistency Napalm gels (8 to 
10 per cent Napalm) and working pressures of 
600 to 1000 psi. Difficulty experienced with 
satisfactory ignition of thick fuels in the port¬ 
able flame thrower indicated that more infor¬ 
mation on factors affecting ignition of fuel dur¬ 
ing flight was also needed. 

Discussion brought out the desirability of re¬ 
taining as much of the fire power of the M5 
tank as possible, while the necessity of provid¬ 
ing adequate fuel capacity for a large flame 
thrower was recognized. The use of a trailer 
was not originally desired, but was ultimately 
adopted. Performance of the tank was not to be 
reduced by more than 50 per cent, and the 


trailer, if adopted, was to be resistant to ma¬ 
chine gun fire. It was desired to use air pressure 
for fuel propulsion, and the question of air com¬ 
pression versus precompressed air was to be 
included as a subject for investigation. 

Preliminary field experiments were carried 
out with two pieces of equipment: a small model 
with i/4-in. jet, and a 300-gal truck-mounted 
model with an experimental gun producing 
14 -in., 1 / 2 -in., and %-in. jets. 

DescriptioiP*'’ ^ ‘ 

Carrier. With the exception of the flame gun, 
all of the flame-thrower equipment was carried 
in an auxiliary armored trailer unit. 

The trailer was mounted on two pneumatic- 
tired wheels, and was attached to the tank 
through a 10 -in. diameter ball-socket joint, 
which permitted the trailer to be turned through 
an angle of 105 degrees from the center line in 
any direction (Figure 25). The fuel line between 



Figure 25. General view of M5A1 light tank 
with trailer unit attached. 


the ball-socket joint and the trailer was braced 
in such a way that it could serve as a drawbar. 
The joint in the hitch was fastened by a toggle 
chain which could be released by remote con¬ 
trol from within the tank if it became necessary 
to jettison the trailer. A special valve, built 
into the joint, prevented loss of fuel from the 
trailer when the joint was open. The fuel line 
had a plug valve before the ball-socket joint to 
shut off the fuel tank when the trailer was dis¬ 
connected (Figure 26). 

The fuel bottle was supported on bent axle 
rods, and the other equipment on a structural 






E9 FLAME THROWER IN M5A1 LIGHT TANK 


127 


steel frame. A skid plate was placed under the 
fuel bottle so that the trailer could be dragged 
over obstructions, and permitted operation at 
reduced speed in the event of a tire failure. 



FROM FUEL TANK 



Figure 26. Sketch of ball-socket joint of hitch 
between trailer and M5A1 light tank with the E9 
flame thrower. 


The available information indicated that an 
M5A1 tank should be able to pull the trailer up 


a 30 per cent grade in loose sand at a speed of 
2 to 3 mph, and in level loose sand at a speed of 
20 mph. 

The total weight of the trailer unit loaded 
was approximately 12 tons. 

Propulsion System. Compressed air was used 
for propulsion of the fuel. The air was supplied 
at 800 psi by two compressors, modified Lycom¬ 
ing 0-435-T airplane engines. This is a six- 
cylinder opposed engine of about 85 hp. Con¬ 
version to a compressor was accomplished by 
removing three cylinders on one side of the 
motor and substituting three two-stage com¬ 
pressor cylinders. The cooling fan on the engine 
provided intercooling. No provision was made 
for aftercooling. The compressed air was stored 
in the fuel bottle itself, directly above the fuel. 

Fuel System. Fuel was carried in a 1,200-gal 
fuel bottle. Normally the bottle would be 
charged with 600 to 800 gal of fuel, the remain¬ 
ing space being used as an air cushion. The 
bottle was of odd shape in order to provide 
high fuel capacity and still keep the height and 
width of the trailer about equal to the height 
and width of the M5A1 tank. It was constructed 
of armor plate, the thickest plates being 1% in. 
Normally, the bottle was charged with pre¬ 
mixed Napalm-thickened gasoline. A large pro¬ 
peller mixer, powered by an air turbine, was 
provided so that fuel could be mixed in the fuel 
tank if this should prove desirable. The line 
which conducted fuel from the fuel bottle to 
the gun unit was of 5-in. DXH pipe. It left the 
fuel bottle at the bottom well forward of the 
center. The outlet was shielded with a baffle 
plate to prevent coning of air into the fuel line. 

Unit. The gun unit was mounted at the 
front center of the tank on a hollow swivel 
fitting which allowed 60 degrees traverse of the 
gun unit to the right or left of the center line. 
After passing through the swivel fitting the 
fuel stream divided into two smaller streams 
which reached the gun unit through hollow 
trunnions, thus permitting elevation, 30 degrees 
from horizontal, and depression, 15 degrees 
from horizontal, of the unit. Motion of the unit 
was controlled by a system of pulleys and cables. 

The duplex gun consisted of two separate 
systems, each with its own nozzle, barrel, and 











128 


MECHANIZED FLAME THROWERS 


pintle valve. The %-in. and V 4 ,-in. nozzles had 
rates of discharge of 7 and 0.7 gal per sec, 
respectively. The guns were mounted in a single 
housing with their axes parallel. The pintle 
valves, mounted in the trunnions, were opened 
by air pressure and closed by fuel pressure. The 
two guns could not be fired simultaneously 
(Figure 27). 

Secondary fuel was distributed over both fuel 
jets before they were ejected from the nozzles. 
The secondary fuel, a mixture of gasoline and 
lubricating oil, was carried in two small tanks 
in the trailer unit. 

Ignition System. Pressure-atomized gasoline 
ignited by a high-tension spark was used to ig¬ 
nite the fuel. The atomizer nozzle was mounted 
between the gun nozzles in such a way that the 
fuel ejected from the gun nozzles passed 
through the cone of gasoline spray ejected by 
the pressure-atomizing nozzle. 


Performance 

Tests of performance were quite incomplete, 
but some data were obtained on operation of 
separate elements.^^ 

Using 10 per cent gel and 500 psi pressure on 
the %-in. orifice, a center-of-deposit range of 
160 yd could be obtained under optimum condi¬ 
tions. With the i/4-in. orifice, the corresponding 
range was 90 yd. Rod ignition was excellent 
with the %-in. orifice, but was affected by 
strong cross winds with the %-in. orifice. The 
ignition mechanism was reliable under all con¬ 
ditions, including immersion in salt water. One 
defect of the gun as installed was limited tra¬ 
verse, only 50-degree total. Elevation as in¬ 
stalled was from —6 to +37 degrees. 

The capacity of the compressor was ade¬ 
quate; in one test, with 300 gal of fuel and 
900 gal of air space in the bottle, the pressure 
was raised from atmospheric to 500 psi in 33 
min. 

The performance of the hitch was very prom¬ 
ising, although it was uncertain whether the 
surface would stand up under continuous rough 
use. 

Trial of the mixing agitator was not suffi¬ 
ciently complete to determine the quality of per¬ 


formance ; visual observation indicated that the 
degree of agitation was adequate. 

When the equipment was ready for actual 
trial, a batch of gel was made up in the bottle, 
which was then pressured to 500 psi.^'* The com¬ 
pressors were started to pressure the fuel bot¬ 
tle, and this proceeded normally up to a pres¬ 
sure of about 400 psi, when the engine for the 
right-hand compressor faltered, necessitating 
taking off the load. Shortly after, the fuel bottle 
exploded and ignited, resulting in demolition of 
the entire trailer, with fatal injuries to per¬ 
sonnel. 

’ ” E13-13 FLAME THROWER IN M4A1 

MEDIUM TANK 

Introduction 

The development of the E13-13 mechanized 
flame thrower for the M4A1 medium tank was 
initiated by Morgan Construction Co. in Feb¬ 
ruary 1944 under Contract OEMsr-1364. This 
development was undertaken in response to a 
Chemical Warfare Service directive, in which 
the general objectives of the project were 
stated as follows (see also Section 5.7) : 

“This development should cover the design of 
a model mounted in M4A1 tank, which may be 
stripped of all items except those necessary for 
the operation of the tank, the radio, and the 
.50-caliber machine guns plus ammunition. It is 
contemplated that a dummy 75-mm gun will be 
installed. The flame thrower should have a mini¬ 
mum effective range of 100 yd, and it is desir¬ 
able to have a burning time approaching 5 min.” 

The E13-13 flame thrower was distinguished 
by the following features: (1) the use of low- 
pressure fuel storage, offering the advantages 
of additional safety and of the use of unconven¬ 
tionally shaped fuel tanks to increase the maxi¬ 
mum quantity of fuel carried; (2) the use of 
synthetic rubber bladders in all fuel containers 
to separate the fuel from the air, thus eliminat¬ 
ing the hazard of accumulation of explosive 
vapors and offering increased safety; (3) the 
installation in the turret of a double pneumatic 
ram system, the cylinders of which alternately 
supplied high-pressure fuel to the flame gun 
from the low-pressure storage tanks. 



E13-13 FLAiSIE THROWER IN M4A1 MEDIUM TANK 


129 


. Description’'^ 

Carrier. The E13-13 flame thrower was 
mounted in the M4A1 tank, modifled to accom¬ 
modate the installation. The main 75-mm gun 
was removed, and a hinged dummy-gun barrel 


stabilizer for the main gun was removed, for 
its use was not felt necessary in conjunction 
with the use of a gun of such relatively short 
range. 

Propellant System. Air was used as propel¬ 
lant for the fuel, and was supplied in two 


GUN SWIVEL CAP- 


crr TWRIl SECONDARY FUEL 
^ ENTRANCE 

GUN 



Figure 27. E9 prototype flame-thrower gun showing the conti’olling mechanism. 


of similar dimensions, housing the igniter chim¬ 
ney and the flame gun, was substituted. The 
auxiliary armament of the tank remained un¬ 
changed, and consisted of one .30-caliber bow- 
machine gun, one .30-caliber coaxial turret 
machine gun, and one .50-caliber turret machine 
gun. 

The firing controls were altered to include 
controls for the flame gun. The turret traverse 
mechanism was left intact, but the gyroscopic 


separate systems. All compressed air for oper¬ 
ating the ram cylinders, igniter, and pilot 
control valves, and for pressurizing the second¬ 
ary fuel was stored in the turret (Fig. 28) in 
3 Navy-type air bottles, which had a safe oper¬ 
ating capacity of 3,000 psi, but were actually 
maintained at 2,000 psi. Two of the bottles had 
a capacity of 4 cu ft each, and the third con¬ 
tained 3.12 cu ft, making the total turret air 
capacity equal to 11.12 cu ft. All three turret air 



























130 


MECHANIZED ELAME THROWERS 


bottles were resiliently mounted in a vertical 
position. 

The hull air supply was provided in six small 
air bottles charged at 2,000 psi, and possessing 
a combined capacity of 2,23 cu ft. This air was 
used for pressurizing the bladders in the main 
fuel tanks at 50 to 70 psi, the reduction in air 
pressure being effected by means of a Grove 



GROSS FUEL CAPACITY 330 GALS 
AIR CAPACITY (6 BOTTLES) 2.3 CU FT 



Figure 28, General arrangement of E13-13 (Mor¬ 
gan) flame-thrower installation. 


regulator located on the side of the hull back of 
the assistant driver’s seat. 

Fuel System. All primary flame-thrower fuel 
was carried in the hull in three tanks, the gross 
capacity of which was 350 gal. Two of these 
tanks, of 115 gal each and cylindrical in shape, 
were located on either side of the driveshaft 
(Figure 29), and the third tank, of odd shape 
and holding 100 gal, was located in the right- 
hand sponson. Each tank contained a synthetic 
rubber bladder to which air was supplied at 
50 to 70 psi, the expansion of the bladders ex¬ 


truding the fuel from the tanks through the 
swivel joint in the turret floor, and delivering 
it to the intake manifold of the pneumatic ram 
unit. All three of the fuel tanks were connected 
in parallel, with outlets feeding into a common 
manifold header connected to the turret swivel 
joint. The fuel-outlet manifold for each fuel 
tank was provided with a quick-acting shutoff 



Figure 29. View looking into hull of M4A1 tank 
showing arrangement of E13-13 fuel tanks. 


valve, accessible to the assistant driver. These 
valves made it possible to supply main fuel 
selectively from any desired tank. 

Damage to the synthetic rubber bags by fuel- 
outlet opening was prevented by molding to the 
bag two hand holes with aluminum inserts 
which covered the outlet ports when the fuel in 
the tank had been exhausted. Flexible connec¬ 
tions were employed as required in the fuel 
lines to allow for differential movement of 
parts. 

Secondary fuel, supplied at approximately 
450 psi, was carried in one 10.6-gal tank located 
in the turret. Igniter fuel was contained in a 
1.56-gal tank. Both these tanks were provided 
with synthetic rubber bladders. 

Pneumatic Ram Cylinders. Located in the 
turret were two pneumatically operated propul¬ 
sion cylinders, which delivered fuel to the flame 
gun at the desired operating pressure. 














































E13-13 FLAME THROWER IN M4A1 MEDIUM TANK 


131 


After passing through the swivel joint, the 
fuel was conducted vertically to the cylinder in¬ 
take manifold, from which it passed to one of 
the two ram cylinders. Each cylinder was 
equipped with a floating piston, and was pro¬ 
vided with an inlet and an outlet poppet valve 
in the upper cylinder head. These poppet valves 
were spring-balanced and automatic in opera¬ 
tion. Air for operating the cylinders was sup¬ 
plied to the lower cylinder heads through a 
four-way air valve, which admitted air alter¬ 
nately to the cylinders, so that only one at a 
time was under firing pressure, whereas the 
other was open to exhaust. Pressure being ap¬ 
plied to a loaded cylinder, the fuel pressure 
automatically closed the fuel-intake valve and 
opened the fuel-outlet valve, permitting fuel to 
flow through the outlet manifold to the main 
pintle valve. Upon exhaustion of the fuel in a 
cylinder, the piston contacted a small lever lo¬ 
cated in a recess in the upper cylinder head, 
and the lever in turn tripped a three-way pilot 
valve, permitting air, under 60 to 80 psi, to 
operate a small air cylinder, which reversed the 
main 4-way valve. This immediately applied 
pressure to the other fully loaded cylinder, 
while the air in the discharge cylinder was 
opened to exhaust. This cylinder then recharged 
with low-pressure fuel, which forced the piston 
to the bottom of the stroke, ready for the next 
cycle. 

Each cylinder had a net capacity of 6 gal. 

Gun. The main armament of the flame 
thrower was the E13 flame gun, which was 
operated by a pintle valve located at the nozzle 
(Fig. 30). Four interchangeable nozzles, %, V2» 
%, and % in. in diameter, were provided. Tur¬ 
ret traverse was 360 degrees; flame gun eleva¬ 
tion was from —12 to +25 degrees. 

Normally, the pintle valve was held closed 
by the pintle spring and air pressure equal to 
or greater than the fuel pressure. When the 
firing circuit was closed, the air back of the 
pintle piston was exhausted through a three- 
way magnetic valve, and the fuel pressure 
forced the pintle to its open position. At the 
end of a shot, the pintle was closed by re¬ 
establishing the air pressure back of the pintle. 
The nozzle pressure under normal operating 
conditions was approximately 300 to 350 psi. 



Figure 30. Dummy-gun barrel showing arrange¬ 
ment of pintle valve and igniter for the E13 
flame gun. 


When firing the gun, a slight interval of time 
occurred during the transition period when 
pressure was shifted from an empty ram cylin¬ 
der to a full one. During this interval, there was 
a momentary drop in the fuel pressure at the 
pintle valve. With the firing trigger held open, 
there would naturally be a tendency for the 
gun to drool during this interval. In order to 
counteract this tendency, a compression spring 
was installed back of the pintle piston, the 
capacity of this spring being such as to cause 
the pintle to close automatically when the fuel 
pressure dropped below 125 to 150 psi and to 
reopen when fuel pressure was re-established. 
A momentary interruption in the jet during the 
change from one ram cylinder to the other re¬ 
sulted from this arrangement. 

Secondary fuel was introduced through a nar¬ 
row annulus located in the convergence to the 
nozzle just back of the point where the pintle 
seats. The secondary fuel was under the same 
pressure as the main fuel, and its flow was 
controlled by a solenoid-operated valve. Under 
normal conditions, the flow of secondary fuel 
was 80 to 100 ml per gal of main fuel. 

lgnitio7i System. The igniter consisted of an 
air-atomized gasoline jet operating at 60 to 80 
psi, and ignited by sparks from two special 
plugs actuated by 2 high-tension coils. The 
atomizer nozzle was mounted inside the cover 
of the dummy gun barrel. 

Performance 

The performance of the E13-13 flame 
thrower, using the V 2 -in. nozzle, closely dupli- 



132 


MECHANIZED ELAME THROWERS 


cated that of the E12-7R1 and E13R1-13R2 
flame throwers, as determined by a special 
CWS-NDRC Mechanized Flame Thrower Eval¬ 
uation Group.It was noted that, while the 
2-in. diameter fuel lines were adequate for feed¬ 
ing a i/o-in. nozzle, they were not adequate for 
assuring optimum results with the larger 
nozzles. 


5 '2 E13R1-13R2 FLAME THROWER IN 

M4A1 MEDIUM TANK 

Introduction 

The development of the E13R1-13R2 mech¬ 
anized flame thrower for the M4A1 medium 
tank was initiated in July 1944 by MIT under 
OSRD Contract OEMsr-21. This development 
was undertaken in response to a Chemical War¬ 
fare Service directive,^^ in which the general 
objectives of the project were stated as follows 
(see also Section 5.7) : 

“This development should cover the design 
of a model mounted in M4A1 tank, which may 
be stripped of all items except those necessary 
for the operation of the tank, the radio, and the 
.50 caliber machine guns plus ammunition. It is 
contemplated that a dummy 75-mm gun will be 
installed. The flame thrower should have a mini¬ 
mum effective range of 100 yd, and it is desir¬ 
able to have a burning time approaching 5 min.” 

Consideration was first given to the advan¬ 
tage of additional safety inherent in low-pres¬ 
sure storage, and the use of fuel tanks of uncon¬ 
ventional shape to increase the quantity of fuel 
carried. However, it was finally decided that the 
space available in the M4 tank lent itself well 
to the installation of fuel tanks of conventional 
shape, so that one of the advantages of low- 
pressure storage was considerably reduced. The 
use of rubber bladders to separate the flame¬ 
thrower fuel from the air in the fuel tanks 
eliminated the hazard of accumulation of ex¬ 
plosive vapors in the tanks, and thus offered a 
promising method of increasing safety. Accord¬ 
ingly, it was decided to combine the rubber- 
bladder technique with a straightforward high- 
pressure fuel storage system. 


^ “ DescriptioiU”’ 

Carrier. The E13R1-13R2 flame thrower was 
mounted in the M4A1 tank, with 76-mm gun 
and wet stowage. This vehicle had two impor¬ 
tant advantages; first, the batteries were lo¬ 
cated in the left sponson, resulting in a reduc¬ 
tion of necessary rewiring; and secondly, 
greater space w'as available in this tank than in 
those mounting a 75-mm gun. 

The main armament of the tank was replaced 
by the E13R2 flame gun, which was mounted 
in a dummy 75-mm gun. The auxiliary arma¬ 
ment of the tank consisted of three .30-caliber 
machine guns, one .50-caliber machine gun, and 
small arms. 

Propellant System. Air was used as propellant 
for the fuel and was supplied in two separate 
systems (Figure 31). The hull system provided 
propellant air for the two hull fuel tanks. The 
turret system provided air pressure for the 
closure of the gun pintle valve, and also sup¬ 
plied air for igniter fuel atomization and for 
propelling the main fuel, secondary fuel, and 
igniter fuel contained in separate tanks located 
in the turret. 

The hull air supply was provided by two 
3.12-cu ft capacity Navy air flasks connected in 
parallel, and another flask of the same size 
served the turret. The air was carried at 2,000 
to 2,500 psi, and the combined capacity of the 
flasks, 9.36 cu ft, was sufficient to give a final 
pressure of about 250 psi in the hull tanks and 
about 550 psi in the turret tank. 

High-pressure hose was used in the air lines 
to insure flexibility of movement between equip¬ 
ment items. 

Fuel System. The fuel system consisted of 
three separate parts: the main fuel system, the 
secondary fuel system, and the igniter fuel sys¬ 
tem. The recommended primary fuel was 
Napalm-gasoline gel of approximately 400 g 
Gardner consistency. In each of the three sys¬ 
tems, air was used as propellant, and contact 
between the air and the fuel was prevented by 
means of synthetic rubber bladders in the tanks. 
The fuel was stored outside the bladders, and 
was expelled from the tanks by inflating the 
bladders with air. 

The main fuel system consisted of two hull 




24V 




CHARGE 


TRIGGER 


FLAME 

thrower 

SWITCH 




MACHINE GUN 
SWITCH 




CHARGE 


FLEXIBLE JOINT 


^>rTtv 


FOOT 

BUTTON 


mmj- 


FOOT 

BUTTON 


machine guns 


iTuRRET 


VENT 


CHARGE 


VENTS 


SLIP 

ring 


CHARGE 


STORAGE 


SECONDARY 


FORWARD 

hull AIR 


AFT 

HULL AIR 


PINTLE a SECONDARY 


VENTS 


DRAIN 


TURRET 
FUEL TANK 


STARBOARD 
HULL FUEL 


PORT 

HULL FUEL 




AiR 




Figure 31. Plow sheet and wiring diagram for E13R1-13R2 flame thrower. 










































































































































































































































































































































































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E13R1-13R2 FLAME THROWER IN M4A1 


133 


fuel tanks located on either side of the vehicle 
driveshaft and the turret fuel tank, together 
with accessories and piping leading to the gun 
in the turret. All three tanks operated in paral¬ 
lel, but it was possible to select either the hull 
or the turret fuel separately by proper setting 
of a three-way fuel valve. 

The fuel capacity of the tanks, in gallons, was 
as follows. 


Two hull tanks 

Turret tank 

Total 

Internal volume 

215 

74 

289 

Capacity with 
bladders in place 

209 

71 

280 

Fuel delivered 

193 

66 

259 


In order to avoid damage to the synthetic 
rubber bags by fuel-outlet openings when the 


the fuel lines to allow for differential movement 
of parts (Figure 32). 

Secondary fuel was carried in one 14-gal 
cylindrical tank located in the turret, and the 
fuel was supplied at approximately 500 psi. Ig¬ 
niter fuel was contained in a 1-gal tank, which 
was designed for a safe working pressure of 
6,000 psi, although operating pressure never 
exceeded 125 psi. Expansion relief valves pro¬ 
tected all fuel systems against pressure due to 
temperature expansion. 

Gun. The main armament of the flame 
thrower was the E13R2 flame gun, which was 
operated by a pintle valve located at the nozzle 
and was provided with interchangeable nozzles 
of %-in., 1 / 2 -in., and %-in. diameters (Figure 
33). The chief advantages of this type of gun 




INCHES 

Figure 32. Cutaway of fuel-tank assembly for E13R1-13R2 flame thrower. 


fuel tanks had been emptied, provision was 
made in the design for a suitably arranged 
spring-loaded poppet valve at each outlet. Flex¬ 
ible connections were employed as required in 


appeared to be simplicity of construction and 
maintenance, and rapid and positive cutoff. The 
disadvantages lay in the fact that important 
control equipment was carried in the dummy 





























134 


MECHANIZED FLAME THROWERS 




























































































































































































































































E19-19 FLAME THROWER IN M4A3 MEDIUM TANK 


135 


gun barrel, which might be shot away in action. 

Normally, the pintle was held closed by the 
pintle spring and air pressure in the pintle 
housing equal to or greater than the fuel pres¬ 
sure. The pintle was operated by releasing the 
air pressure in the pintle housing, permitting 
the fuel pressure to move the pintle backwards 
against the force of the spring to full open posi¬ 
tion. Admittance of air to the pintle housing 
closed the pintle. The nozzle pressure under 
normal operating conditions was approximately 
300 to 350 psi. 

Secondary fuel, controlled by a solenoid- 
operated valve, which was activated by the 
same circuit as the three-way air valve con¬ 
trolling the air and pintle, was admitted to the 
nozzle through a large number of radial orifices 
located just back of the position of the pintle 
seat on the nozzle. 

Ignitioyi System. The igniter was an adapta¬ 
tion of that used on the E7 gun (see Section 
5.3). It consisted of an air-atomized gasoline 
jet which was ignited by high-tension sparks 
from two special plugs. The atomizer nozzle was 
mounted inside the cover of the dummy gun 
barrel. In order to prevent muzzle fires from 
igniter gasoline, a special air-operated atomizer 
control valve was installed just in the rear of 
the pintle-valve body. 


Performance 


Typical range data are cited in the following 
tabulation. 


Nozzle, in. 

ja 


Range, yd 

Firing time, sec 

90-105 

200 

110-125 

110 

125-140 

70 


A special CWS-NDRC Mechanized Flame 
Thrower Evaluation Group set up at Edgewood 
Arsenal carried out extensive tests of the per¬ 
formance of the E13R1-13R2 flame thrower, 
and arrived at the conclusion that the function¬ 
ing of the unit was substantially faultless.^® The 
group found that the ranges obtained with this 


“ This size was later replaced by the %-in. nozzle. 


unit closely duplicated those obtained with the 
E12-7R1, in the description of which they are 
reported in more detail. 


5.13 e\9-19 flame thrower IN M4A3 

MEDIUM TANK 

Introduction 

The development of the E19-19 mechanized 
flame thrower for the M4A3 medium tank re¬ 
taining its main armament was initiated by 
Iowa University under OSRD Contract OEMsr- 
1480 in April 1945. Until that time, emphasis 
had been placed on the development of mechan¬ 
ized flame throwers which displaced the main 
armament of the armored vehicle, this displace¬ 
ment being considered necessary in order to 
obtain sufficient fuel capacity in existing tanks. 
On the basis of objections to the resulting lack 
of fire power and the need for supporting tanks 
during combat operations, work was undertaken 
on the design of a flame thrower with a large- 
capacity flame gun and fuel storage, combined 
with full main armament and adequate am¬ 
munition. 

The M4A3 medium tank, equipped with a 
76-mm gun with wet ammunition stowage in 
the hull, was selected as the basic vehicle, the 
following requirements being imposed upon the 
design. The gun, as well as all other existing 
armament, was to be retained, although about 
half of the 76-mm ammunition-stowage capacity 
was to be sacrificed to make room for the 
flame-thrower installation. The tank silhouette 
was to be altered as little as possible, and the 
modifications to the tank were not to displace 
any member of the tank crew. The flame gun 
employed in the design was to be capable of 
operation with conventional thickened fuel and 
liquid secondary fuel. The nozzle diameter was 
set at % in., and the main fuel pressure was to 
be about 450 psi; otherwise, it was proposed 
to employ any current flame gun best fitted for 
the design with as few modifications as possible. 
The flame thrower was to be capable of field 
installation in existing M4A3 tanks, all neces¬ 
sary equipment being supplied in kit form. 








136 


MECHANIZED FLAME THROWERS 


Work on the development of the E19-19 was 
halted at the end of World War II because of 
obsolescence of the M4 tank. Prior to termina¬ 
tion, the design for the flame gun and mount 
had been completed, working drawings for all 
parts of this assembly being nearly ready. A 
wooden “mock-up” of the flame gun assembly 
had been completed, and working experimental 
models of the flame gun proper and of the 
ignition system had been constructed, and were 
ready for tests. 

5.13.2 Preliminary Location Studies 

Preliminary to the detailed design of the 
mechanized flame thrower, studies were made 
as to placement of the flame gun on the tank 
structure. These studies resulted in the ex¬ 
amination of six different plans by means of 
layout drawings and scale models (Figure 34). 



Figure 34. Various positions of flame-thrower 
gun installation for E19 mechanized flame 
thrower. 


The plans were numbered 1 through 6; Plans 
2 and 3 were abandoned at an early stage; and 
Plan 5 was finally adopted for the location of 
the flame gun and mount. 

Plan 1 Coaxial Gun-Shield Mount. This plan 
mounted the flame gun on the main gun shield, 
on the port side of the 76-mm gun; thus the 
flame gun shared the elevation and depression 
limits of the 76-mm gun, viz. -1-25 to —10 de¬ 
grees. Elevating, traversing, and sighting con¬ 
trols were the same as used for the 76-mm gun. 
Because of insufficient available space near the 
76-mm gun, the flame gun flexible joints could 


not be mounted on the axis of rotation, and 3 
such joints were therefore required. 

Plan 2 Starboard Coaxial Gun Mount. The 
design differed from Plan 1 only in that the 
flame gun was mounted on the starboard side 
of the 76-mm gun, and was abandoned because 
it offered no advantage over Plan 1. 

Plan 3 Starboard Fro7it Turret Mount. This 
plan mounted the flame gun above the main 
gun shield and to the starboard of the 76-mm 
gun, and elevation of the gun was accomplished 
through a linkage to the 76-mm gun. This 
design had the disadvantage of insufficient 
space for adequate armor without interfering 
with the gunner’s vision, and it was therefore 
abandoned in favor of the generally similar 
Plan 5. 

Plan U Center Froyit Hidl Momit. This de¬ 
sign was attractive because it required no slip 
ring below the turret. Flame gun traverse was 
180 degrees; elevation was from +60 to —10 
degrees. A complicating factor was the possi¬ 
bility of interference between flame gun and 
76-mm gun. 

Pkm 5 Port Turret Momit. This plan was 
selected for full development. The flame gun 
was mounted to the left of the gun shield, and 
was attached to the turret. The flame gun trun¬ 
nion axis was collinear with the 76-mm gun 
trunnion axis. Flame gun elevation, obtained 
by a 2:1 gearing connected to the main gun 
shield, was from +50 to —20 degrees. Detailed 
description of this gun mount is presented else¬ 
where in this section. 

Plan 6 Pistol Port Momit. This plan utilized 
the pistol-port opening for mounting the flame 
gun, permitting traverse of 360 degrees with 
the turret and elevation from +60 to —10 de¬ 
grees. 

5.13.3 Description of Approved Design 

Carrier. The E19-19 flame thrower was to be 
mounted in the M4A3 tank, which retained its 
main armament but was slightly modified to 
accommodate the flame-thrower system. The 
right side of the hull was made available for 
main fuel storage, at the sacrifice of slightly 
less than half of the 76-mm ammunition-stow¬ 
age capacity. Secondary and igniter fuel were 



E19-19 FLAME THROWER IN M4A3 MEDIUM TANK 


137 


to be carried in the turret, while the compressed 
air for the expulsion of the main fuel was to be 
stored on the right sponson. The flame gun 
mount consisted of a blister to the port side of 


cutting off the left end of the shield 19.5 in. 
from the 76-mm center line and welding on a 
transition section to replace the cutoff portion. 
This transition section served the dual purpose 





CHECK VALVE 
REGULATOR 


STRAINER 


PRESSURE GAUGE 


Figure 35. Flow diagram for E19-19 flame-thi'ower installation. 


the turret in such a manner that the axis of 
elevation of the flame gun coincided with the 
trunnion axis of the 76-mm gun. The gun shield, 
as it existed in the M4A3, was modified by 


of providing a shield for part of the flame gun 
blister and of transmitting the motion of the 
76-mm gun to the flame gun. 

Propellcnit System. Compressed air was con- 







































































138 


MECHANIZED FLAME THROWERS 


templated as propellant in the E19-19 flame 
thrower, the air for expelling the main fuel 
being stored at 3,000 psi in 1 cylinder of 3 cu ft 
capacity located in the right sponson, while the 
air for expelling the secondary fuel and atom¬ 
izing the igniter fuel was stored at 3,000 psi in 
one cylinder of 0.5 cu ft capacity located in the 
turret. The compressed-air cylinder communi¬ 
cated with the fuel tanks through pressure regu¬ 
lators, maintaining 390 psi over the main fuel, 
440 over the igniter fuel. The high-pressure 
air storage cylinders were equipped with safety 
heads set at 3,750 psi. 

Fuel System. The main fuel for use in the 
E19-19 flame thrower was to be thickened gaso¬ 
line, stored in a 100-gal fuel tank in the hull 
and a 30-gal fuel tank in the right sponson 
(Figure 35), the fuel tanks being equipped with 
550 psi relief valves and 700 psi safety heads. 
The limited fuel capacity of 130 gal resulted in 
a total firing time of 25 to 30 sec for the %-in. 
nozzle recommended. 

The secondary fuel consisted of liquid gaso¬ 
line, stored in one 4-gal container located in the 
turret. Secondary fuel was normally to be sup¬ 
plied at the rate of 3 per cent of total fuel, but 
the exact rate was controllable by means of a 
throttle valve. Igniter fuel was stored in one 
0.5-gal fuel tank in the turret, allowing the 
use of the fuel at a rate of 2 gal per hr for twice 
the total firing time. 

Gun. The flame gun used in the E19-19 flame 
thrower was essentially a modified combination 
of the 1-3 gun and the E13 gun (see Sections 
5.9, 5.11, 5.12). The E19 gun employed the same 
pintle and spring as was used in the E13 gun; 
provision was also made for admitting sec¬ 
ondary fuel around the nozzle in the same loca¬ 
tion relative to the pintle valve, and the internal 
contours of the nozzle were quite similar to 
those of the E13 gun (Figure 36). The E19 
gun resembled the 1-3 gun in that the main fuel 
feed came in at right angles to the axis of the 
flame gun, and the axis of rotation for elevation 
coincided with the fuel line. To permit elevation 
and depression, a simple slip joint was provided. 
Main fuel cutoff was at the pintle valve. The 
nozzle diameter was % in. 

The flame gun could be elevated and de¬ 
pressed in a 2 :1 ratio with respect to the 76-mm 


gun, the actuating torque being supplied from 
the special extension attached to the 76-mm 
gun shield. This ratio was accomplished by the 
use of a pinion gear on an actuating arm mesh¬ 
ing with a stationary gear sector on one side 
and a similar sector on the other side attached 
to the gun. Maximum elevation was 50 degrees, 
maximum depression was 20 degrees, from the 
horizontal. Traverse was full 360 degrees. 

Ignition System. The ignition system of the 
E19 gun substantially resembled that of the 
E13 gun, although the mechanical details dif¬ 
fered considerably. The two spark plugs were 
Champion 0a45-Ex. 1, and were mounted in 
such a manner as to be removable from the 
front. The spark-plug wires led from the spark 
plugs forward along grooves in the ignition 
barrel, and ultimately returned through the 
turret wall to the source of high tension neces¬ 
sary for operation of the spark. 

The atomizer nozzle was the same as in the 
E13 gun (De Vilbiss Model 5100), and was 
located in almost the same position. The total 
axial length from the front tip of the pintle 
valve to the spark-plug point at the ground 
electrodes was 9 in. The distance from the tip 
of the atomizer nozzle to the spark point at the 
ground electrodes was 6.25 in. 

Controls. Flame gun elevation and depression 
control was effected by use of the 76-mm gun 
elevation hand wheel; traversing control was 
obtained by rotating the turret. 

Individual firing controls were contemplated 
for the igniter fuel and for the main fuel. The 
igniter control, a foot pedal, turned on the fuel 
and air to the atomizer nozzle and actuated the 
sparks. The trigger-operated main fuel control 
simultaneously exhausted the air behind the 
pintle valve, thus allowing the latter to open 
under the main fuel pressure, and opened a 
valve in the secondary fuel line to permit flow 
of secondary fuel into the flame gun nozzle. 

Sighting for the flame gun was through the 
gunner’s periscope, which would have to be re¬ 
built to function properly as a sighting device 
for both guns. This rebuilding would have to 
include the provision of a 2/1 actuating linkage 
to permit the periscope to be rotated either 
directly with the 76-mm gun or at twice the 
angular rate with the flame gun.^’^ 



MAIN GUN SHIELD 


E19-19 FLAME THROWER IN M4A3 MEDIUM TANK 


139 



FUEL CHARGING CONNECTION ^COUNTERWEIGHT 














































































































































































140 


MECHANIZED ELAME THROWERS 


’“ E20-20 (T33) FLAME THROWER IN 
M4A3 MEDIUM TANK 

Introduction 

The development of the E20-20 was begun in 
May 1945, with the Standard Oil Development 
Co. under Contract OEMsr-390 acting as con¬ 
sultants."'-^ This particular development of in¬ 
stalling a long-range, large-capacity flame gun 
in an M4A3E2 (heavily armored M4A3), with 
the main armament retained, resulted from the 
success of the British Crocodile tank-trailer 
unit and the POA Model with the 75-mm cannon 
and flame gun mounted coaxially. In addition 
to the cannon and flame gun, it was planned to 
install a small auxiliary turret flame thrower, 
E21 (CWS periscope gun E6). Although pro¬ 
jecting through separate turret shields the 
flame gun E20, improved Model Q or E7, and 
the 75-mm cannon are essentially coaxially 
mounted. To accommodate these weapons, it 
was necessary to design a special turret. The 
construction was done by M. W. Kellogg with 
the CWS and Ordnance furnishing additional 
help. Upon termination of Contract OEMsr-390, 
basic design of the flame-thrower installation 
had been completed and a trial mockup made 
in the hull. Prior to the termination of World 
War II it was anticipated that the E20-20 
(T33) would ultimately replace the M5-4 (E12- 
7R1) main-armament, medium-tank flame 
thrower then in commercial production (Figure 
37). 


Description^ 

Carrier. The E20-20 (T33) was mounted in 
an M4A3E2 (heavily armored M4A3) medium 
tank (Figure 38). The major difference between 
the standard M4A3E2 and the flame-throwing 
installation was the special turret with broad¬ 
ened front, extended rear overhang, slightly 
increased height, approximately 4 in., and a 
double-barrel main armament. 

The 75-mm gun was an M-6 light weapon 
which was employed in aircraft and in the M-24 
light tank. This weapon was chosen principally 
because the assembled unit was smaller than 


the 75-mm cannon normally installed in United 
States medium tanks, providing more working 
space in the turret and permitting sufficient 
clearance for installation of the special ]M5-4 
flame-thrower rotary joint in the basket floor. 
The M-6 used standard 75-mm ammunition, of 



EFFECTIVE * 2 VESSELS IN 
HULL (HORIZONTAL, BAFFLED) , 

2 VESSELS IN BASKET 
(OBLIQUE) 

(SERIES FLOW) 

Figure 37. Simplified flow plan of flame-thrower 
tank T-33. 

which 5 to 10 ready rounds were carried in the 
E20-20 basket to augment the 40 to 45 rounds 
stowed in the right sponson. 

Propellant System. Propellant gas was stored 
in 2 segregated systems at an initial pressure 
of 3,000 psig, this high starting pressure being 
employed to minimize storage space require¬ 
ments and allow maximum room for stowage 
of 75-mm ammunition. Main propellant gas was 
carried in seven horizontal cylinders, 6 cu ft 
total, connected in parallel and located in the 
sponsons and hull. Sufficient space was allowed 
to store 75-mm ammunition on the forward 
right sponson shelf. Propellant gas from the 
seven containers discharged through a pressure 
regulator to the top of the right hull main fuel 
tank, maintained 375 to 4,000 psig operating 
pressure behind the fuel. Auxiliary propellant 
gas was stored in a 1-cu ft vertical cylinder be- 











































£20-20 FLAME THROWER IN M4A3 MEDIUM TANK 


141 



Figure 38. Model of T-33 flame-thrower tank. 

Note enlarged turret and dual guns. 

hind the gunner in the left rear basket. This 
supply through pressure regulators furnished 
propellant pressure for secondary and igniter 
fuels for the E20, igniter air for the E20 atom¬ 
izer nozzle, and operating pressure for both the 
E20 and E21 flame guns. 

Fuel System. The same main fuel supplied 
both the E20 and the E21 flame guns, and was 
carried in four cylindrical pressure containers, 
270 gal gross capacity, piped in series. Two of 
these vessels were horizontal containers with 
internal baffles for improved outage located in 
the hull beneath the turret basket (Figure 39), 
which was shortened approximately 7 in. to ac¬ 
commodate the containers. The hull fuel system 
was piped to the turret through a special rotary 
joint (same as employed in the E12-7R1 me¬ 
dium-tank flame throwers) in the center of the 
basket floor. The rotary joint carried both main 
fuel and multiple electrical power and inter¬ 
phone circuits from the hull to the turret, dis¬ 
charging flame-thrower fuel in to the turret 
fuel containers. Two main fuel containers were 
located beneath the turret roof, each vessel 
sloping downward to the rear for improved 
outage (Figure 40). These vessels straddled the 
tank commander’s position in the rear center 
of the turret basket, and discharged forward 
along the right turret wall to the trunnion el¬ 
bows feeding the E20 flame gun. A valved 
feeder from this line also led through a flexible 
hose to the E21 periscope gun. Approximately 
260 gal of main fuel was charged through a 
protected connector in the turret roof, flowing 
in reverse through the fuel system to the hull 


containers and overflowing, when filled, from 
the right hull vessel through an external vent. 

Secondary fuel was stored in a vertical con¬ 
tainer, 12.3 gal, behind the loader in the right 
rear basket. This fuel was delivered into the 




LOOKING FORWARD 

Figure 39. Flame-thrower tank T-33 (E20-20) 
in M4A3E2 medium tank showing schematic lay¬ 
out of hull. 

E20 flame gun at 500 to 550 psig through the 
main control valve, which simultaneously 
opened the weapon internal fuel valve. Pending 
development by CWS of necessary E21 modi¬ 
fications, it was tentatively planned to supply 
secondary fuel from the source described above 
to the periscope flame gun. This would permit 
the auxiliary flame thrower to use heavier 
thickened fuels, commonly employed with larger 
flame guns and relatively difficult to ignite with¬ 
out secondary fuel in adverse winds or in cold 
or wet weather. The supply of secondary fuel 
was based upon anticipated employment of both 
main and auxiliary flame throwers. Secondary 
fuel filling and venting was effected through 
protected external openings adjacent to the 











































142 


MECHANIZED ELAME THROWERS 


main fuel charging connection in the turret 
roof. 

E20 Gu71. The E20, a slightly modified E7R1 
flame gun, has been described in Section 5.3. 


traverse of the auxiliary flame gun, relative to 
the turret, over approximately a 240-degree arc 
to the rear. The E21 gun will be limited to the 
elevation and depression available through the 
periscope holder, forward fire from the turret 


E2I PERISCOPE FLAME- 
6UN{2400TRAVERSEc 
TO REAR OF 
TURRET) 



SPECIAL CAST 
ARMOUR TURRET 
(360°TRAVERSE) 


-E20 FLAME GUN 
(-l5PTO+4^ ELEVATION) 


_ ■^UGHTLY 

INCREASED INTERNAL' 
OVERHEAD CLEARANCE 
COMPARED WITH I 
STANDARD TURRET — 


SECONDARY FUEL 

container 

"AUXILIARY AIR 
CONTAINER 

Iatomizer fuel 

!< CONTAINER 




-SPECIAL COz 
SYSTEM (HULL) 


TURRET BASKET 
(APPROX 7IN.SHORTER 
THAN STANDARD) 


MAIN FUEL 
CONTAINERS 
(HULL) 


SIDE ELEVATION 


AUXILIARY AIR CONTAINER 
I CU FT 3000 PSI 

TANK COMMANDER 
VISION CUPOLA 


MAIN FUEL CONT 
350-400 PSI 25 GAL 

GUNNERS ROOF 
HATCH 



MAIN FUEL 
CONT 350-400 
PSI 25 GAL 

SECONDARY FUEL 
CONT 12.3 GAL 
500-550 PS 


-ATOMIZER 
FUEL CONT 
1.2 GAL 5-10 PSI 


LOADERS 

ROOF 

HATCH 


-DUMMY MUZZLE 
TUBE FOR E 20 
FLAME GUN 


TURRET PLAN VIEW 

Figure 40. Flame-thrower tank T-33 (E20-20) 
in M4A3E2 medium tank showing schematic lay¬ 
out of turret. 


The major difference was the length of the noz¬ 
zle extension, which was 21 in. for the E20. The 
auxiliary flame gun, E21, was designed for flank 
protection in jungle or close fighting, and was 
the CWS periscope gun E6 which could be in¬ 
stalled or removed quickly in the field. The E21 
could be mounted in the normal manner through 
the periscope holder in the center of the tank 
commander’s vision cupola. This vision cupola 
was located in the rear center of the turret 
roof over the tank commander’s position in the 
basket, and provided for limited direct manual 



Figure 41. E7 gun mount for pump-operated 
flame thrower. 


being eliminated to preclude firing into the 
turret roof at maximum E21 depression. The 
remaining operation of the gun remains the 
same. 

Ignition System. Atomizer or igniter fuel 
for the E20 flame gun is carried in a 1.2-gal 
vertical container adjacent to the secondary 
fuel tank. This fuel flows at 5 to 10 psig through 
a dual atomizer valve which is actuated by the 
E20 main fuel-firing pedal and simultaneously 
delivers gasoline and air to the atomizer noz- 






























PUMP-OPERATED FLAME THROWER IN MEDIUM TANK 


143 


zle ejecting into the dummy tube ignition cham¬ 
ber. Protected external filling and vent connec¬ 
tions are adjacent to those for secondary fuel 
in the turret roof. 

The E20 ignition system consists of atom¬ 
izer fuel, atomizer air, and electrical circuits 
simultaneously actuated by the flame gun-firing 
pedal prior to opening of the internal fuel valve. 
Atomizer fuel and air form gasoline spray in 
the dummy gun tube ignition chamber to be 


5.1.5 PUMP-OPERATED FLAME THROWER 
IN MEDIUM TANK 

Introduction 

An experimental investigation of pump-oper¬ 
ated flame throwers was begun in 1945 by the 
Eastman Kodak Co, under OSRD Contract 
OEMsr-538. Earlier attempts at pump-pro¬ 
pelled flame throwers in 1942-1943 had been 



Figure 42. Experimental pump-operated flame thrower mounted on Buick chassis. 


ignited by dual sparks. Dual spark-coil boxes 
feed 12,000 v potential to the ignition-spark 
plugs from the vehicle 12-v d-c supply, deliv¬ 
ered through the firing pedal ignition switch. 
The ignition system is identical with the E12- 
7R1, described in Section 5.7, a simplified flow 
plan of which is shown in Figure 18. 


Performance 

Performance data on the flame throwers in¬ 
stalled in the E20-20 was not obtained at the 
time of writing, since the units had yet to be 
completed. 


unsatisfactory, and compressed gas was ac¬ 
cepted as a standard means of fuel propulsion. 
In 1944 a theoretical paper on the relative 
merits of pump propulsion as opposed to com¬ 
pressed gas was published.^® In this paper the 
results of calculations, based upon certain as¬ 
sumptions, indicated that pump propulsion pos¬ 
sessed an advantage over the accepted com¬ 
pressed-gas method only with units having 
small nozzles and large fuel capacity. In the 
light of this, pumps received little attention 
until early 1945 when a reconsideration of the 
theoretical aspects of pumps, especially with 
regard to pump speeds, indicated a possible ad¬ 
vantage in their use.’^' Accordingly, NDRC 







144 


MECHANIZED FLAME THROWERS 


launched a project to study the behavior of fuels 
in pump-propelled flame throwers. 

Preliminary experiments with several pumps 
and jets indicated that the characteristics of 
the pump-propelled jet differed somewhat from 
the gas-compressed flame thrower.^®-These 
differences called for the incorporation of sev¬ 
eral new features of design. Besides the substi¬ 
tution of a pump for the air bottles, a surge 
chamber has been introduced to eliminate the 
pulsating due to the pump action, a blower has 
been added to maintain a positive pressure on 
the fuel tank, and a by-pass system has been 
used to permit the pump to operate at low 
pressures. Since the object of the project was 
to demonstrate the advantages of a pump-pro¬ 
pelled flame thrower, it was not considered ad¬ 
visable to design a new gun. Therefore, the E7 
gun was used, though this made necessary the 
provision of a pump for the secondary fuel and 
a small compressor to supply compressed air 
to actuate the valves. 

Description®"'^^’'^^ 

The Eastman pump-operated flame thrower 
shown in Figures 41 and 42 may be briefly de¬ 
scribed as follows: An Imo screw pump utiliz¬ 
ing standard rotors, the same size as those of 
the Imo A32P, is mounted inside a rectangular 
fuel tank. This tank is mounted on a Buick 
chassis and the power for the pump is taken 
from the Buick driveshaft by means of a chain 
drive. The discharge of the pump passes 


through a four-way pilot-operated hydraulic 
valve in conjunction with an ordinary relief 
valve, thence through a surge chamber and to 
the standard E7 flame gun. Provision is made 
for pressurizing the main fuel tank to about 
5 psi by means of a rotary positive-displacement 
blower. Air pressure for actuation of the valves 
of the E7 gun is provided by a small compressor. 
The flow design is shown in Figure 43. 

The Pump. The Imo pump, specially designed 
for the purpose, is fitted with a large bell-mouth 
inlet placed 1/2 in. above the floor of the fuel 
tank. The outlet at the top of the pump is 2 in., 
and the piping is standard 2 in. with extra 
heavy fittings. 

By-Pass System. The four-way hydraulic 
valve with its relief valve is mounted directly 
above the pump inside the fuel tank. The sole¬ 
noid-operated pilot valve is mounted at the top 
of the fuel tank with leads from the main fuel 
pump and to the four-way valve as shown in 
Figure 43. With the pilot valve open, the four¬ 
way valve passes the fuel back to the tank at low 
pressure. With the pilot valve closed, the fuel 
passes to the flame gun line. The maximum 
pressure in either line, by-pass or flame gun, is 
limited to 440 psi by a regular relief valve which 
returns any excess fuel to the supply tank. The 
pilot valve, which controls this system, is actu¬ 
ated by a 12-volt solenoid. 

The Fuel Tank. The fuel tank is 26x26x66 in., 
approximately 185 gal; the bottom and the end, 
through which power and piping connections 
pass, are of %-in. steel plate. The remainder. 


1. l-in. Kodak Park standard type flame arrester. 

2. %-in. standard 125-lb quick-opening valve. 

3. %-in. Star brass 10-lb relief valve. 

4. B-W superchargers blower, 3,600 rpm, 20 cfm, at 5 

psi. 

5. 15-gal drum type gas tank. 

6. IP, 739 C 500 psi, 5 gpm, 1,000 rpm, (by-pass) Pesco 

pump. 

7. %-in. 500-lb Vickers relief valve. 

8. %-in. solenoid actuated pilot valve. 

9. 2-in. 400-lb Ashton hydraulic relief valve. 

10. 1% in. 1,500-lb pilot operated Logansport four-way 

valve. 

11. Special 32P 231 1,800 rpm, 150 gpm, 500-lb Imo 

pump. 

12. Kodak Park designed surge chamber. 

13. Grove reducing valve, 500-lb to 7-lb for igniter 

gasoline. 


14. S 21 National foam generator, navy-type mixer 

injector, 2-in. pipe. 

15. Regular E7 flame-thrower gun. 

16. Shield. 

17. Grove reducing valve, 1,650-lb to 500-lb for pintle 

actuation and gun control. 

18. Cornelius compressor, 1,500-lb, 52 cu in. per 12 min, 

weight 10-lb, 24-v, d-c motor. 

19. Grove reducing valve, 1,650-lb to 50-lb for igniter 

air. 

20. 1,500-lb air bottle, 200 cu in. 

21. Four 6-v batteries to give 24 v. 

22. Standard 39 Buick transmissions. 

23. Morse silent-chain transmission system, l-% x %-in. 

pitch. 

25. Double V-belt drive for Pesco pump. 

26. Single V-belt for BW superchargers blower. 


Figure 43. Flow diagram of Eastman pump-opei’ated flame thrower. 





IIleft hand 
. GRIP 


RIGHT HAND 
GRIP 




FUEL 

TANK 


d zi W // // // // i y/ //'y/r4> // y/I 


1st THA»)^ 


2N0 than 8 


MAIN FUEL LINE 

INJECTION AND RECIRCULATION 

AIR LINES 

SECONDARY FUEL 

IGNITER FUEL 

BATTERY LINES 

PILOT LINES FOR FOUR-WAY VALVE 
BLOWER SYSTEM FOR MAIN TANK 















































































































































































































































































































































































































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■.■••> -*— fc ■ 







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u * - - * ' *1 '^S 1* ' * ‘ V ^ 








PUMP-OPERATED FLAAIE THROWER IN MEDIUM TANK 


145 


except for a 24x24-in. manhole, is Va-hi. plate 
strengthened with horizontal pressed ribs 8V2 
in. apart and l^xi/^-in. vertical bars tack- 
welded 9 in. apart inside the tank. The tank will 
withstand 20-psi hydrostatic pressure without 
any appreciable distortion. Its total weight in¬ 
cluding a 90-lb, 26x26 %-in. steel plate cover is 
635 lb. 

A blower which can supply air to the fuel 
tank up to 7 psi at the required rate has been 
installed in order to overcome cavitation at the 
pump inlet as the boiling point of gasoline is ap¬ 
proached. 


is set to operate whenever the pressure in the 
air bottle drops below 1,500 psi. The bottle pres¬ 
sure is reduced to 500 psi for gun actuation and 
50 psi for atomizer air by means of regulators. 
The gasoline for secondary and ignition fuel is 
supplied by a fuel-injection pump which de¬ 
livers at 500 psi the 5 gal per min required for 
secondary fuel and through a reducing valve 
(7 psi) the 0.05 gal per min required for igni¬ 
tion fuel. 

Power Source. The unit is powered by a Buick 
engine equipped with compound carburation. 
Power for the pump is transmitted by a chain 


Table 2. Comparison of pump-operated and air-pressurized flame throwers. Eastman pump-operated flame thrower 
on Buick chassis with 3^-in. regular nozzle (E7-R1 Gun) vs E12-7R1 flame thrower with H-in. extension nozzle (in 
M4A1 tank). 


Fuel for both guns, 6% Imperial 230 g Gardner Nozzle height above ground: E12-7R1, 7)^ ft; EPOFT, 6 ft 


Code 

No. 

Gun 

elev. 

Rpm 

Main fuel 
pump 

Main fuel pressure 

Surge 

chamber 

pres. 

operating 
(preloads to 
100 psig) 

Wind 

velocity 

mph 

Wind 

direction 

Range! 
Center of 
deposit 

Pump or 
fuel tanks 

Nozzle* 

Pt 

5° 

1,500 

400 

340 

360 

1 

Cross 

85 

SOD§ 

5° 


350 



0 


83 

P 

10° 

1,500 

380 

340 

360 

0 


100 

SOD 

10° 


350 



0 


100 

P 

10° 

1,250 

270 

250 

240 

3 

Cross 

87 

SOD 

10° 


300 



3 

Cross 

85 

P 

10° 

1,350 

305 

270 

265 

1 

Head 

97 

SOD 

10° 


350 



1 

Head 

97 

P 

4° 

1,250 

265 

240 

235 

1.5 

Cross 

83 

SOD 

4° 


350 



1.5 

Cross 

87 


♦Measured 3 ft behind nozzle. {EPOFT. 

{Each value represents the average of two runs. §E12-7R1. 


Surge Chamber. The surge chamber consists 
of a synthetic rubber bag in a 3-in. perforated 
tube, both being enclosed in a 4-in. pipe. The 
fuel passes through the annular space between 
the bag and the outer shell. The rubber bag is 
preloaded with air to a pressure lower than 
the operating pressure of the pump. Its con¬ 
tractions and expansions remove pressure pul¬ 
sations from the pump discharge. Only by this 
design of a surge system of minimum inertia 
was it found possible to remove pump pulsa¬ 
tions sufficiently to protect the fuel jet against 
breakup in the air. 

Flame Gun. The compressed air for the E7 
gun is furnished by a small compressor which 


drive, and power for the blower and secondary 
pump by V-belt drives from the main pump 
shaft. 

Performance 

Pulsations. The serious pulsations associated 
with earlier pumps w'ere not found in the pres¬ 
ent Imo pump. With the surge chamber pre- 
loaded to 100 psi, and with operating pressures 
of 200 to 330 psi, no visible pulsations were re¬ 
corded. However, when the pre-loaded pressure 
was increased to a pressure higher than oper¬ 
ating pressure, equivalent to no surge chamber, 
a pulsation of but 1 to 2 psi was obtained. A 
























146 


MECHANIZED FLAME THROWERS 


major function of the surge chamber is that of 
absorbing shock when going from low to high 
pressure or closing the main gun valve. 

Range. A fuel of approximately 250 Gardner 
gives an effective range of 100 yd using a Vo-in. 
nozzle and 200- to 350-psi pressure. The range 
data compare favorably with those of the E12- 


7R1 flame thrower operating under similar con¬ 
ditions (Table 2).*’- 

Holdup. The fuel left in the tank after chan¬ 
neling first occurred was about 6 in. for a 6 per 
cent fuel and 8 in. for an 8 per cent fuel. This 
amounts to 20 to 30 per cent of the total fuel 
capacity. 


entia: 




Chapter 6 

MISCELLANEOUS FLAME WARFARE ITEMS 


‘*1 INTRODUCTION 

T his chapter describes a variety of miscel¬ 
laneous developments and investigations 
undertaken by Division 11 of NDRC in con¬ 
junction with the general field of fiame warfare. 
These activities comprised work on fuel mixing 
and flame-thrower servicing equipment, the de¬ 
velopment of devices for the utilization of self- 
igniting fuels, investigations into the casualty- 
producing effects of flame, and the devising of 
countermeasures against flame attack. 

^* 2 E8 AND E8R1 SERVICE UNITS 
Introduction 

With the development of mechanized flame 
throwers requiring up to 300 gal of Napalm- 
thickened fuel and approximately 4 cu ft of 
2,000 psi air per 100 gal of thickened fuel, it 
became necessary to develop equipment which 
could supply these weapons in the field. To ful¬ 
fill this requirement, a project to design a mo¬ 
bile flame-thrower servicing unit was initiated 
in November 1943 by Standard Oil Develop¬ 
ment Co. under Contract OEMsr-390.i Later 
equipment was assembled by the Davey Com¬ 
pressor Co. under Contract OEMsr-1266. 

Information was already available on the 
simple batch process of mixing fuel for portable 
flame throwers.- Some consideration was given 
to continuous mixing methods but none were 
readily available, and it appeared that a con¬ 
tinuous process would require considerable de¬ 
velopment work. 

In cooperation with CWS the following gen¬ 
eral requirements were established for flame¬ 
thrower service units. 

1. Air compressor must be balanced in 
capacity with fuel-mixing capacity, approxi¬ 
mately 4 cu ft 2,000 psi air per 100 gal of thick¬ 
ened fuel. It must be light in weight but rugged 
and compact for mobile field use. The discharge 
pressure requirement was raised from 2,000 to 
3,000 psi in February 1945. 


2 . Mixing facilities must be simple and 
rugged, of maximum capacity as permitted by 
carrying vehicle, and capable of operating in 
all theaters on available Napalm thickeners. 

3. Vehicle must be standard U.S. Army type, 
capable of traveling as close to the combat lines 
as the unarmored vehicles which commonly 
supply armored units. For most areas the Army 
considered the 2V2-ton 6x6 truck to be ade¬ 
quate, but for special operations, such as on 
beaches and swampy or mountainous terrain, 
amphibious or tracked carriers would be re- 
quired.'"^ 

Description 

Preliminary Units. To meet the above field 
requirements, the following features were in¬ 
corporated in preliminary units: 

1. Early studies showed that a 2V2-ton 6x6 
truck would be seriously overloaded when 
carrying a skid-mounted, engine-driven air com¬ 
pressor of adequate capacity as well as fuel¬ 
mixing equipment. To reduce overload and bulk, 
it was necessary to eliminate separate engine 
drives through the use of a power take-off 
which permitted all equipment to be driven by 
the truck engine. This required the factory 
mounting of equipment on the truck, reduced 
the availability of the vehicle for hauling mis¬ 
cellaneous cargo, but assured maximum mo¬ 
bility when servicing advancing mechanized 
flame throwers. 

2. A new, high-pressure air compressor de¬ 
veloped by the Clark Bros. Co. under Contract 
OEMsr-370, Model HO-6-4, six-cylinder, four- 
stage, air-cooled, 63 cfm, was selected as the 
lightest weight machine available with the 
desired capacity. 

3. Development work on fuel mixing included 
tests to determine the pumpability of thickened 
fuels containing from 4 to 10 per cent Napalm. 
It was found that heavy-duty, positive-displace¬ 
ment gear pumps were entirely satisfactory, 
provided the suction head was sufficient to keep 
the pumps filled with fuel. This study also pro- 


147 


148 


MISCELLANEOUS ELAME WARFARE ITEMS 


vided necessary data on the pressure drop 
through pipes and the power required to pump 
thickened fuel.-* 

These units prepared and delivered 500 gal 
of thickened fuel and compressed 25 cu ft of 
2,000 psi air per hr.^ From the experience with 
these units, various weight-saving changes 
were made, reducing the truck overload from 
60 to 16 per cent with considerable simplifica¬ 
tion of equipment, and resulting in the E8 
service unit (Figure 1).*' 


pressor in order to deliver a maximum pressure 
of 3,000 psi (E8R1 service unit). 

Mixing Tank and Fuel Pump. The mixing 
tank was cone-bottomed and had a capacity of 
280 gal. To thoroughly agitate the Napalm and 
gasoline, the tank was provided with a power- 
operated propeller stirrer. In cool weather when 
mixing became difficult, it was possible to heat 
the contents of the tank by circulating hot cool¬ 
ant from the truck engine through a jacket sur¬ 
rounding the tank. 


COMPRESSOR 



Figure 1. E8R1 servicing unit in place on 2%-ton truck. 


Air Compressor. The Clark Bros, air com¬ 
pressor incorporated in the preliminary unit 
was found to perform satisfactorily. The com¬ 
pressor was capable of a maximum pressure of 
2,250 psi (E8 service unit), but later require¬ 
ments made it necessary to modify the com- 


The fuel pump was of the gear type and had 
a capacity of 35 gal per min at 175 psi. 

Poiver Supply. As has been indicated, the 
power for the various units was provided by 
the truck engine through a heavy-duty power 
take-off, belts and countershaft. 











E6 MIXER AND E8 COMPRESSOR 


149 


Performance 

Procedure. In operation the service unit 
functioned in the manner outlined below (Fig¬ 
ure 2). 

1. Gasoline was pumped into the mixing tank 
from the available source, i.e., drums or tank 
truck. 

2. Napalm was poured into the tank and the 
contents were agitated by a power-driven pro¬ 
peller until thickening was complete. 

3. The thickened fuel was pumped into the 
tanks of the flame thrower. 


II terminated before the units were put into 
operation. 

E6 MIXER AND E8 COMPRESSORS- 
Introduction 

In order to provide service equipment equiva¬ 
lent in capacity to the E8R1 service unit, but 
capable of transportation in amphibious or 
tracked vehicles over terrain not suited to a 
standard truck, the design of a skid-mounted 
unit was assigned in January 1945 to the Stand- 



Figure 2. View of E8R1 servicing unit and M5-4 mechanized flame thrower. 


4. While the above was being accomplished, 
the compressor was pressuring the flame 
thrower. 

For 280 gal of fuel the entire operation re¬ 
quired about 30 min. 

Servicing Tests. Both the Standard Oil De¬ 
velopment Co. and the various branches of the 
Army conducted a series of service tests which 
showed that the unit was completely satisfac- 
tory.’’’- ^ The unit was capable of delivering 560 
gal per hr of thickened fuel containing from 
4 to 8 per cent Napalm at atmospheric tempera¬ 
ture between 20 F and 100 F. Fuels containing 
10 per cent Napalm could be produced at a 
somewhat lower rate. 

A total of 65 of these units were actually 
produced by the Davey Compressor Co. under 
Contract OEMsr-1266. However, World War 


ard Oil Development Co. under Contract 
OEMsr-390.11 Relatively little development 
work was required because of the experience 
gained in establishing the E8R1 service unit 
design. However, the arrangement and mount¬ 
ing of the equipment was new (Figure 3).^- 

Description 

E6 Mixer. The E6 mixer incorporated a 13- 
hp, four-cylinder, Wisconsin gasoline engine 
driving a gear-type fuel pump and a mixing 
propeller located in a 285-gal cone-bottomed, 
batch-mixing tank, with fuel hoses and other 
accessories, all mounted on a heavy skid.®- 
For low temperatures the mixer could be 
heated by supplying coolant from the engine¬ 
cooling system to the jacket of the mixer. 










130 


MISCKLLANFOI S FLAMF: AKFARF ITEMS 


Performance 



Figurk 3A. View of E6 mixer mounted on skid. 

PJ8 Comprefifior. The E8 compres.sor con.sisted 
of a modified Navy type-40 compre.ssor, Inger- 
soll-Rand Model GC-50-BW, .six-cylinder, four- 
stage, liquid-cooled, set to deliver air at 2,250 
psi, and mounted on a skid with its gasoline 



The compressor E8 had a capacity of 27 
cu ft per hr of 2.000 psi air, and the mixer 
capable of mixing 560 gal of thickened fuel per 
hr (Figure 4). These rates were equal to the 
rates developed by the E8R1 .ser\*ice unit, but 
the E8R1 weighed half as much as the com¬ 
bined weights of the E6 and E8 units. A com¬ 
parison of the units will be found listed in 
Table 1. These were subjected to preliminary 
seiwice te.sts by various boards, and all units 
performed .satisfactorily.^^ 


Table 1. Comparison of units E8R1, E6, and ES. 


Mount 

E8Pvl 

E6 E8 


2Tton 6x6 
Army truck 

Skid 

Portability 

Fixed on2T 

Amphibious, full- 


ton Army 

tracked, or wheeled 


truck 

vehicles 

Power 

Power take- 

13-hp 57-hp 


off from 
21-ton truck 
engine 

gas engine gas engine 

Capacity gal of 
thickened 

fuel/hr 

560 

560 

Cu ft; hr of 3,000 

psi air 

26 

27 

Weapons serviced 

2 E14-7R2 

or 2 M5-4 (E12-7R1) 
per hr 

Wt of servicing 
equipment lb, 
exclusive of 

vehicle 

5,760 

4,800 6,900 

Dimensions of serv¬ 
icing equipment 

Overall length, in. 

104 

107 105 

Overall width, in. 

79 

68 74 

Max height, in. 

64 

80 SI 


^ FERRO-CLEAVER BROOKS :MIXING 
UMTi" 

Introduction 


Figure 3B. View of E8 compressor. 

engine and all accessories. Tackle was provided 
with each unit to facilitate handling and load¬ 
ing onto vehicles. The compressor is shown in 
Figure 3B. 


To fill the field requirements for a small mix¬ 
ing device for continuous mixing of Napalm 
and gasoline, a project was begun in February 
1944 by the Ferro-Drier & Chemical Co. under 
Contract OEMsr-1281. Originally the equip¬ 
ment was to be a readily portable, hand-oper- 


















FERRO-CLEAVER BROOKS MIXING UNIT 


151 



Figure 4. Mixer E6 and air compressor E8 in position for servicing mechanized flame thrower. 



® © 


A 

Napalm hopper. 

G 

Gasoline metering pump. 

B 

Napalm helical feeder. 

H 

Grinder. 

C 

Funnel for gasoline and Napalm to be ground. 

I 

Gasoline heater. 

D 

Funnel for gasoline and Napalm to remain un- 

J 

Mixing tee. 


ground. 

K 

Gel discharge hose. 

E 

Pump to pass gasoline and Napalm to grinder. 

L 

Gasoline inlet hose. 


F Pump to pass gasoline and Napalm to mixing tee. 

Figure 5. Flow diagram of Ferro mixer. 


atecl mixer, capable of mixing concentrations 
between 2 and 8 per cent of the various types of 
Napalm. As the development progressed, the 
many complicated problems of mixing led to a 
more elaborate design. 

At the expiration of Contract OEMsr-1281, 
the project was continued by Ferro-Drier under 
a sub-contract of the Eastman Kodak Co. Con¬ 
tract OEMsr-538. Since Ferro-Drier did not 
have suitable manufacturing facilities, the proj¬ 


ect was finally turned over to the Cleaver- 
Brooks Co. for completion. 


Description 

Introduction. In Figure 5 the schematic flow 
diagram of the mixer is shown. Essentially, 
the process consisted of feeding Napalm at a 
fixed rate with preheated gasoline and forcing 










































152 


MISCELLANEOUS FLAME WARFARE ITEMS 


the mixture through a grinder. This concentrate 
was then mixed with a secondary gasoline 
stream. If a more concentrated final product 
was desired, additional Napalm was added, 
without grinding, to the secondary stream. The 
unground mixture was prevented from settling 
by the viscosity of the ground mixture, and the 


tion. The rate of delivery of Napalm could be 
adjusted by means of a slide at the bottom of 
the hopper which permitted smaller or larger 
portions of the paddle to be exposed to the 
Napalm. Correction was made for the bulk 
density of the Napalm by measuring the height 
to which one can, e.g., 514 lb, of Napalm filled 



A On-off switch in magneto pri¬ 
mary circuit. 

B Circuit breaker cam. 

C Momentary-on switch to cutout 
controls. 

D Magneto. 


E Fenwal temperature overload 
switch, open at high temperature. 
F Persons pressure switch. 

G Sylphon fuel valve, closed at 
low pressure. 

H Spark plug. 

I Stewart Warner sealed heater. 


J Maxim spark arrester. 
K Gasoline outlet. 

L Gasoline inlet. 

M Heater fuel line. 
iV Combustion air line. 

O Fuel spray nozzle. 


Figure 6. Flow diagram of gasoline-heater system showing electrical circuit. 


total grinding necessary was kept to a mini¬ 
mum. The mixture became homogeneous after 
setting. 

Metering Device. Work with various meter¬ 
ing devices led to a hopper feeder with a ro¬ 
tating paddle wheel below it. The pockets of 
the paddle wheel were filled with Napalm and 
would deliver a given volume with each rota- 


the hopper, and setting the adjustment ac¬ 
cordingly. The rate of delivery of Napalm to 
gasoline was coordinated by directly connect¬ 
ing the Napalm feeder to the Blackmer vane 
pump which metered the gasoline. 

Grinding Devices. After various experiments 
it was found that if the Napalm-gasoline slurry 
could be forced through a fine-toothed gear 























































Ell MIXING UNIT 


153 


pump running backwards, sufficient grinding 
could be obtained almost eliminating the set¬ 
tling of the Napalm. If stirred for about 20 to 
30 sec after this grinding, no further settling 
of the Napalm occurred. The grinding process 
was later improved by substituting for the re¬ 
verse gear-pump grinder a series of perforated 
rotating disks separated by perforated stators. 
The chief objection to the disk type of grinder 
was the additional horsepower that was re¬ 
quired. 

Heater. Unless the temperature of the gaso¬ 
line was about 90 degrees, mixing was unsatis¬ 
factory. To raise the gasoline to this tempera¬ 
ture, a small gasoline heater consisting of con¬ 
centric shells of large, stainless steel tubes was 
devised (Figure 6). This type of heater was 
able to heat 300 gal of gasoline per hr through 
a temperature rise of 45 degrees. Situations 
were visualized in which this capacity would 
be inadequate. In addition, the heater was diffi¬ 
cult to manufacture, and to keep clean. 



Figure 7. View of Ferro mixer on base plate. 

Power Device. From the original idea of a 
hand-operated mixer, the apparatus grew so 
extensive that the need for power drive arose. 
A small, one-cylinder gas engine was installed 
and found to be satisfactory when operating at 
a rate of 2 gal per min of mixed fuel. When the 
unit was redesigned for greater ruggedness and 
the disk type of grinder introduced, a motor of 
15 hp was required. These improvements in¬ 


creased the weight to 1,000 lb, a much heavier 
unit than field operations would allow. 


^ Performance 

The unit as originally designed by Ferro- 
Drier (Figure 7) was tested at Edgewood Ar¬ 
senal and found to be inadequate for the follow¬ 
ing reasons: (1) it was under-powered; (2) 
there was excessive vibration; (3) the pre¬ 
heater lacked capacity; and (4) the grinder 
and pumps were inadequate. 

From these tests and additional development 
work by the Cleaver-Brooks Co., it appeared 
that a different approach should be considered. 
This led to the Ell mixing unit described in 
the next section. 


Ell MIXING UNIT 
^ ^ Introduction 

When the Ferro-Drier mixing unit was 
turned over to the Cleaver-Brooks Co. for man¬ 
ufacturing under sub-contract of Eastman 
Kodak Co., Contract OEMsr-538, the Cleaver- 
Brooks Co. also initiated a new approach to the 



Figure 8. Ell mixing unit mounted on jeep. 

problem of field mixing. The result of their 
efforts was a simplified drum-type, circulating 
mixing unit Ell that could be conveniently 
transported in a jeep (Figure 8).^^ 








154 


MISCELLANEOUS FLAME WARFARE ITEMS 


Description 

In Figure 8 the layout for the mixing process 
including a heater is shown. Raw gasoline 
is pumped from some storage source to the 
mixing drum, illustrated in Figure 11, into 
which the required amount of Napalm is 
dumped. The pump circulates the slurry until 
mixing is complete, at which time the gel is 
pumped to the storage tank. This entire process 
is controlled by two 2-way valves, one located 
on the suction side of the pump and the other 
on the storage side. The two pumps, operating 


a temperature rise of 60 F. Its weight was 
approximately 160 lb. 


Performance 

Tests indicated that the unit could satisfac¬ 
torily mix most Napalms of 3 to 8 per cent con¬ 
centrations at a rate of 500 to 600 gal per hr, 
provided the gasoline was 90 F or above. For 
lower temperatures, with the pre-heater in the 
line, the rate is reduced to 250 gal per hr (Fig¬ 
ure 9). 



MIXING 

TANK 


PUMP 


STORAGE 

TANK 


STORAGE 

TANK 


RAW 

GASOLINE 


HEATER 

1 


MIXING 

TANK 


Figure 9. Ell mixing unit with heater in position. 


independently of each other, are driven by a 
2-cylinder, 4-cycle gasoline engine. 

In a cool environment the temperature of 
the raw gasoline must be raised to about 90 F 
in order that mixing may be accomplished in a 
reasonable length of time. For this purpose a 
heating unit of the coil-and-tube, gasoline-fired 
type, driven by a gasoline engine, was devel¬ 
oped as illustrated in Figure 10. The heater was 
designed to heat 20 gal of gasoline per min in 


Some trouble was encountered when very fast 
setting Napalms were used. In these cases the 
gels would set so rapidly that some of the 
Napalm would not be mixed into the gasoline. 
The majority of the unmixed Napalm could be 
taken up after the lumps were broken up and 
particles forced through the pump. For the 
Navy-ground Napalm, which must be intro¬ 
duced into the gasoline stream rather than into 
the drum, the National Foam type venturi 





NAVY iVIARK I MIXING UNIT 


155 


mixer was tried. Metering difficulties with the 
apparatus led to the use of the Ferro-Drier pad¬ 
dle wheel feeder mentioned in the previous sec¬ 
tion. This operated fairly satisfactorily al¬ 
though the paddle wheel tended to become 
gummed from the splashing of the gasoline. 



Figure 10. Gasoline heater with Ell mixing unit. 

NAVY MARK I MIXING UNIT 
Introduction 

The Mark I Napalm mixing unit was devel¬ 
oped by the Navy; NDRC was informally in¬ 
vited in July 1944 to act as technical consult¬ 
ants. The development of the jettisonable fuel 
tank as a fire bomb introduced the problem of 
obtaining a rapid Napalm mixing unit to fill 
the tank with thickened fuel after the empty 
fire bomb was attached to the plane. Such a unit 
had to be capable of rapidly mixing a 6 per cent 
Napalm-gasoline gel which could be forced into 
the jettisonable fuel tank. In addition, since a 
large portion of the mixing had to be done for 
carrier-based planes, freedom from fire haz¬ 
ards and portability were requisites. 


Description 

The mixing unit introduced the Napalm into 
the gasoline stream by the venturi principle 
as the gasoline passed through a venturi at a 
rate of approximately 30 gal per min.’" From the 
venturi, the stream containing the dispersed 


Napalm continued through a short section of 
hose of approximately li/4 in. ID and 20 ft in 
length, and finally discharged through a con¬ 
trollable orifice into the jettisonable tank. The 
ground Napalm was poured into a funnel-like 
hopper perpendicularly superimposed on the 
venturi. The gasoline stream was pressurized 
by the tank-pressuring system of the ship or 
by a small pump, if the process was done on 
land. 



Figure 11. View of interior of barrel in which 
mixing occurs. 


* Performance 

The introduction of the finely ground Napalm 
into the gasoline stream through the venturi 
to produce a turbulent suspension of the soap 
in the liquid was intended to give good disper¬ 
sion leading to the formulation of a homo¬ 
geneous gel. The upstream pressure of the 
stream was maintained at 25 psi; the down¬ 
stream back-pressure was 5 to 10 psi. The con¬ 
trollable discharge orifice served to regulate 
the percentage of Napalm concentration by con¬ 
trolling the pressure at the venturi. The unit 
was operable unaided within the normal tem¬ 
perature range established for Napalm mixing; 
however, with the use of an accelerator (xylenol 







156 


MISCELLANEOUS FLAME WARFARE ITEMS 


or cresylic acid) good gelation had been obtained 
at temperatures as low as 8 F. 

This device was simply constructed and could 
be improvised from fire-fighting equipment. 
When gasoline was transported in drums or 
tanks, the unit could have a small engine-driven 
rotor pump (standard equipment), discharging 
approximately 30 gal per min, added to the 
venturi system to supply the pressure. 


■ El ANTI-PERSONNEL TANK PROJECTOR 
Introduction 

The development of the El anti-personnel 
tank projector was initiated in December 1944 


a near-by foxhole or concealed position and 
held a mine to the side of the tank until it de¬ 
tonated. This usually resulted in considerable 
damage to the tank, and in the death of the 
attacker. The problem of defense against such 
attacks was complicated by several factors, 
among them the very rough terrain of opera¬ 
tions, which prohibited the employment of any 
devices projecting materially beyond the exist¬ 
ing outlines of the tank, and the limited range 
and angle of vision of the tank commander, 
which made it difficult to observe directly the 
approach of enemy personnel carrying mines 
to the tank. On the other hand, the tank com¬ 
mander possessed the advantage of direct radio 
communication with near-by ground forces, who 
frequently warned him of the approach of an 



by Arthur D. Little, Inc., Contract OEMsr-242. 
The device is essentially a small special-purpose 
flame thrower which is mounted externally, in 
multiple, on tanks to ward off enemy personnel 
attempting to attack the vehicle by means of 
hand-borne bombs or mines. 

Many tank casualties had resulted from ac¬ 
tion in which an enemy approached a tank from 


enemy and indicated the general direction of 
approach. 

The eutectic mixture of phosphorus and phos¬ 
phorus sesquisulfide (EWP) which spontane¬ 
ously ignites upon contact with air and which 
had been previously evaluated as a flame¬ 
thrower fuel (see Sections 4.4, 6.8, and 8.8), 
appeared to have promise as a fuel for a special- 





















































157 


El ANTI-PERSONNEL TANK PROJECTOR 


purpose flame thrower adaptable for coping 
with the situation described above. A simple 
device easily attachable to a tank was accord¬ 
ingly designed, constructed, demonstrated, and 
placed in limited procurement under a special 
contract with CWS. 


Description 

A complete description of the El anti-per¬ 
sonnel tank projector in its final form appears 
elsewhere.Figure 12 illustrates the device, 
which is an electrically controlled flame thrower 
delivering a blanket of flame covering areas 
within 15 yd of the vehicle. The nozzle of the 
device can be adapted to produce almost any 
fan-shaped field of fire desired. The fields of 



Figure 13. Exterior view of El anti-personnel 
tank projector. 

or any combination can be fired simultaneously. 
The combined 15-yd and 10-yd forward jets on 
either side are fired simultaneously. 

The only parts of the device mounted inside 
the armor of the vehicle are the electrical con- 



Figure 14. El anti-personnel tank projector showing three units firing simultaneously (right-front unit 
not firing). 


fire adopted were evolved from actual tests on 
M4 tanks at Edgewood ArsenaP*^ and Fort 
Knox.-'^ For this coverage, four individual 
flame-thrower units are used. Each unit is con¬ 
trolled electrically from within the vehicle by a 
push-button switch; any unit can be fired alone. 


trols. These consist of a lead from the main 
24-volt supply to a stationary contact box about 
5 in. long, 4 in. wide, 2 in. high, which is bolted 
to the hull, just forward of the turret ring on 
an M4A3. This box contains a master switch 
which can be locked either off or on. When this 

g'liiLD [1^ 









158 


MISCELLANEOUS FLAME WARFARE ITEMS 


switch is on, a warning light shows both on 
this box and on the portable box mentioned 
below. The fixed box also contains a set of four 
firing buttons. Two-conductor armored cables 
about in. in diam run from this box to each 
of the four flame-thrower units. A six-conduc¬ 
tor portable cable about 1/2 in. in diam runs to 
a portable control box intended for use within 
the turret by the tank commander. This box is 
only 2 in. in diameter and about 3 in. deep, and 
can be worn on the chest without imposing a 
burden greater than 20 oz. It may also be hung 
on any convenient hook. 

The flame-thrower unit consists of a 1-gal 
pressure tank containing the EWP fuel and 
accessory equipment which supplies carbon 
dioxide at a regulated pressure of about 75 psi 
to the tank (Figure 13). The solenoid valve 
controls delivery of the fuel under pressure to 
the nozzle. The fuel tank and carbon-dioxide 
system are arranged in cartridge form for 
simplicity and safety in reloading. Cartridge 
units can be either factory-charged with both 
the fuel and carbon dioxide, or charged at ad¬ 
vanced bases by trained personnel with a small 
amount of charging equipment. 

Although the EWP fuel ordinarily ignites 
spontaneously immediately upon ejection, igni¬ 
tion is further assured by providing a small 
electrically operated “hot finger” heating ele¬ 
ment near the flame-thrower nozzle. 

^ Performance 

In tests at Edgewood ArsenaP^ and at Fort 
Knox-*’’-^ of the El anti-personnel tank projec¬ 
tor in its early form, the device was found to 
function satisfactorily for the general purpose 
intended (Figure 14). Following these tests, 
minor changes were made, after which final 
acceptance tests were carried out at Norwood, 
Massachusetts. The Norwood tests also ade¬ 
quately proved the absence of excessive con¬ 
tamination of the tank exterior due to dripping 
or scattering of fuel. In spite of the small quan¬ 
tity of EWP fuel charged, it was established 
that each 1-gal unit was capable of firing be¬ 
tween 20 and 30 effective bursts before requir¬ 
ing a new charge. 


“ « STUDIES OF PHYSIOLOGICAL EFFECTS 
OF FLAAIE 

Introduction 

An investigation into the physiological effects 
of flame attack against occupants of an enclosed 
structure was initiated in August 1944 by 
Arthur D. Little, Inc. under Contract OEMsr- 
242. The work was undertaken primarily as 
part of an experimental program for the evalu¬ 
ation of EWP as a special flame-thrower fuel, 
compared with conventional Napalm-thickened 
gasoline, and the experiments were devised with 
a view toward providing such a comparison, 
rather than to furnish complete data on the 
effect of either fuel alone under a variety of 
conditions.-- 


Experimental Work 

Pillbox. The enclosed fortification used for 
evaluating the casualty-producing effects of 
flame-thrower fuels was a German type con¬ 
crete pillbox of hexagonal shape. The external 
length of each edge was 11 ft and the walls 
were 4 ft thick, so that the internal length of 
each edge was 6 ft. The height of the pillbox 
above ground was 71/2 ft, the floor level was 2 
ft below ground, and the roof consisted of a 
concrete slab 1 ft in thickness. The total volume 
of the pillbox was 900 cu ft. 

A loophole with intricately designed ap¬ 
proaches was provided in each wall of the struc¬ 
ture, and access to the pillbox was through a 
31 / 2 x 3 ft entrance under one of the loopholes. 
The pillbox was provided with a Y^-shaped, 
radially symmetrical baffle, constructed of con¬ 
crete blocks, each leg of the baffle being 32 in. 
wide and 8 in. thick. The baffle separated the 
pillbox into three equal compartments, desig¬ 
nated respectively as the door compartment, the 
fire compartment, which included the loophole 
attacked, and the off compartment. 

Fuels and Flame Thrower's. The fuels used 
were 4 per cent Napalm-gasoline gel shot from 
a standard M2-2 portable flame thrower, and 
EWP fuel (described in Section 8.4) shot from 



COUNTERMEASURES AGAINST FLAME THROWERS 


159 


a special flame thrower (described in Section 
4.4). 

Animcd Experiments. Two series of experi¬ 
ments were conducted to gain information on 
the casualty-producing effects of the two flame¬ 
thrower fuels studied. In the first series indi¬ 
vidual small white domestic swine were used as 
the experimental animals. The instrumentation 
attached to the animals during attack included 
pneumograph, thermocouples, special disks to 
measure caloric bombardment, and electrocar¬ 
diograph. Conditions within the pillbox were 
determined by continuous recording of tem¬ 
peratures and gas compositions of representa¬ 
tive locations. 

In the second series of experiments, rabbits 
were used along with pigs, and six of each 
species were simultaneously exposed in each 
test, one rabbit and one pig being suspended by 
means of Fiberglas cords in each of six repre¬ 
sentative locations. 

The experiments consisted in placing the ani¬ 
mals in predetermined positions within the pill¬ 
box, installing the various instruments and 
starting their operation, and finally attacking 
the pillbox by injecting a measured quantity of 
the fuel under test, usually 1 gal, into the pill¬ 
box from a fixed distance. At the conclusion 
of each experiment, the animals were removed 
from the pillbox for autopsy and microscopic 
inspection of tissues. 

Conclusions 

The following general conclusions were 
reached as a result of this work. 

1. One gal each of 4 per cent Napalm-gaso¬ 
line and of EWP were compared in field experi¬ 
ments involving pigs and rabbits in a concrete 
pillbox. 

2. External burns were more extensive and 
severe in shaved pigs exposed to EWP than in 
similar animals exposed to Napalm, 

3. Damage to the coat and skin burning 
were slightly more severe in rabbits exposed to 
Napalm than in those exposed to EWP. 

4. Arranged in order of decreasing hazard to 
occupants from the point of view of burns, the 
pillbox compartments are: fire, off, door—high 


positions being more dangerous than low posi¬ 
tions. 

5. No clear relation between position in the 
pillbox and incidence of respiratory damage 
was indicated. 

6 . The respiratory lesions were chiefly patchy 
atelectasis and emphysema, pulmonary conges¬ 
tion, oedema, and hemorrhage. 

7. Less prevalent were tracheobronchial 
lesions. 

8 . EWP produced greater respiratory dam¬ 
age than Napalm. 


COUNTERMEASURES AGAINST FLAME 
THROWERS 

Introduction 

Development work on countermeasures 
against flame attack was initiated in August 
1944 by Arthur D. Little, Inc., under Contract 
OEMsr-242, The work was undertaken in re¬ 
sponse to a directive received from the Navy 
Department, Bureau of Ships, Damage Control 
Section, under Project N5-317, and its general 
objective consisted in studying possible counter¬ 
measures against flame attack upon enclosed 
spaces, and devising methods and equipment for 
putting such countermeasures into effect.-^ At 
that time, studies of the physiological effects of 
flame were being conducted in a German type 
pillbox at Norwood, Massachusetts (see Section 
6 .8), and it was decided to use the facilities 
available at Norwood for the work on counter- 
measures. 


Experimental Work 

Prelimmary Work. The conditions prevailing 
in the Norwood pillbox during flame attack 
from a portable flame thrower using 4 per cent 
Napalm-gasoline gel had been thoroughly in¬ 
vestigated and the action of the flame upon un¬ 
protected pigs and rabbits placed in various 
positions within the enclosure had received ex¬ 
haustive study. 

In view of the findings resulting from the in- 




160 


MISCELLANEOUS FLAME WARFARE ITEMS 


vestigation of conditions prevailing in the pill¬ 
box during flame attack, it was postulated that 
the primary lethal action of flame under the 
conditions studied was thermal, respiratory 
damage being only a contributory factor. In 
consequence, it was decided to concentrate the 
initial stages of the work upon protection by 
means of ultra-rapid fire extinguishment.-^ 

In this connection, the application of water 
fog appeared to present especially attractive 
possibilities, and several experiments were 
made to test the effectiveness of water fog in 
extinguishing fires. 

For the production of water fog, several 
nozzles were procured from two manufacturers; 
all of these nozzles produced a satisfactory fog. 

Water-Fog Curtains. Attempts to extinguish 
ignited rods of thickened gasoline with “fog 
curtains” directed parallel to the loophole of at¬ 
tack resulted in little success, and showed that 
the principle of fog curtains as such is not use¬ 
ful for the purpose contemplated. Even with the 
largest fog nozzle tested, it was very seldom 
that extinguishment of an ignited 4 per cent 
Napalm-gasoline gel was complete when the 
gel was injected into the pillbox from a distance 
of 10 yd from an MlAl flame thrower. In most 
instances, some fuel would arrive in the pillbox 
ignited, and any extinguished fuel would catch 
fire from it. 

Napalm Extinguishment. A permanent water 
line was constructed to the pillbox, and a fog 
nozzle was placed near the ceiling of the fire 
compartment, the fog being directed toward 
the base of the baffle inside the pillbox. It was 
found that such an arrangement was extraor¬ 
dinarily effective in extinguishing Napalm- 
gasoline gels injected from a flame thrower 
within a very short time, and with small quan¬ 
tities of water. It was found that, with any one 
of the nozzles tested, it was usually possible to 
extinguish the entire 4.5 gal of fuel within 2 to 4 
sec, using between 0.3 and 0.8 gal of water. 

Liquid Fuels. Extinguishment of liquid fuels, 
whether gasoline or gasoline and heavier oil 
mixtures, is quite difficult to accomplish with 
water fog when the burning fuel is introduced 
by being injected with a flame thrower. Re¬ 
ignition of partially extinguished fuel persists 
for so long a time that the protective value of 


fog would probably be nullified. 

Fog Applicator. A small portable fog appli¬ 
cator was designed and built. This applicator 
consists essentially of a 6-gal steel vessel capa¬ 
ble of withstanding approximately 200-psi pres¬ 
sure and equipped with a water-filling tube, a 
pressure attachment, and a water-outlet tube 
leading to a flexible metal hose, valve, and fog 
nozzle. The vessel can be filled only partially 
with water, leaving a gas space, which is pres¬ 
sured from a small carbon dioxide or nitrogen 
cylinder attached to the vessel. The applicator, 
filled with water and compressed gas, is ready 
for use, and several such applicators can be 
placed in the structure to be protected, the 
nozzle being fixed in predetermined positions. 
In addition to these fixed installations, one or 
two portable applicators with movable nozzles 
play serve to extinguish stray gobs of burning 
fuel. 

Immediately upon the first indication of flame 
attack the occupants of the structure attacked 
would pull a chain, or several chains, which 
would actuate quick-acting valves releasing 
water fog in the structure. The fog would be 
applied until all fire is extinguished. In the Nor¬ 
wood pillbox, it is believed that three fixed 
nozzles and two portable nozzles would be suf¬ 
ficient to serve this purpose. 

Tests with Animals. A number of experi¬ 
ments with animals were carried out to test the 
effectiveness of water-fog extinguishment as a 
countermeasure against the anti-personnel ac¬ 
tion of flame. 

In all experiments a full charge of 4 per cent 
Napalm-gasoline gel was injected into the pill¬ 
box from a distance of 10 yd. Extinguishment, 
whenever attempted, was carried out with a 
fog nozzle operating under 100-psi water pres¬ 
sure. The nozzle was placed in the pillbox, 6 ft 
above the floor, and the fog was directed toward 
the base of the baffle. Temperatures were meas¬ 
ured in the three compartments at 4-ft eleva¬ 
tion. Gas samples were taken at the same loca¬ 
tions. Total combustibles in the gas, i.e., largely 
gaseous hydrocarbons, were measured in the 
locations indicated by means of a Cities Service 
power prover. In some of the experiments pro¬ 
tective clothing was used on the animals, either 
alone or in combination with water fog. 







PROTECTION OF SHIP CONNING TOWERS AGAINST SUICIDE PLANE ATTACK 161 


Conclusions 

1. Water fog offers an ultra-rapid method 
of extinguishing flaming Napalm-gasoline gel 
in a pillbox with small volumes of water. 

2 . The extinguishment of liquid fuels is more 
difficult. 

3. A simple device has been designed for ap¬ 
plying water fog in the field. 

4. Partial protection against flame attack 
may be accomplished with water fog. 

5. Even the ultra-rapid extinguishment does 
not avail against severe momentary flash burns. 

6 . Water and clothing alone have not afforded 
complete protection to animals in the experi¬ 
ments, but the degree of casualty is limited by 
their use. 

7. The unburned fuel which floats on the 
water after extinguishment may offer a con¬ 
tinuing hazard of reignition. This can possibly 
be corrected by additional drainage. 

8 . Danger is introduced by the asphyxiating 
and explosive potentialities of atmosphere high 
in hydrocarbon vapors. 

9. All possible information should be ob¬ 
tained about special protective fabrics, and an 
attempt should be made to evaluate under serv¬ 
ice conditions the usefulness of a garment which 
could be constantly worn. 

6.10 protection of ship conning towers 

AGAINST SUICIDE PLANE ATTACK 
Introduction 

The investigation of countermeasures against 
suicide plane attacks upon conning towers of 
warships was undertaken in February 1945 by 
Arthur D. Little, Inc., under Contract OEMsr- 
242. During the latter part of World War II 
considerable loss of life and damage was being 
inflicted by Japanese crash-diving planes loaded 
with liquid fuel, and thus it became imperative 
to develop effective methods for protecting the 
occupants of enclosed spaces, such as conning 
towers, from the heat and fumes generated by 
the burning fuel. For this study an actual 
conning tower of a ship was set up in coopera¬ 


tion with the Damage Control Section of the 
Bureau of Ships, U.S. Navy, at the Boston Fire 
Fighters’ School. 


Approach 

Burning fuel about an enclosed tower will 
raise the internal temperature of the tower 
through heat transfer and will fill the interior 
with flames and gases, provided there are any 
open ports. By providing some method of clos¬ 
ing the ports,the remaining problem is one of 
reducing the heat transfer through the walls 
of the tower. 

In order to evaluate the effect of different 
variables and the effectiveness of any counter¬ 
measures, it was necessary to establish some 
means of measuring the heat transfer. For this 
purpose two criteria, thermal efficiency and 
countermeasure index, were introduced. Ther¬ 
mal efficiency represented the ratio of the total 
heat input to the walls, as measured by the 
temperature increase and total heat capacity 
of the conning tower, to the total heat available 
from the fuel used. The thermal efficiency rep¬ 
resented a convenient method of evaluating the 
effect of external variables such as wind and 
drainage on the amount of heat transferred.-^ 
As the project progressed the need for evaluat¬ 
ing internal countermeasures led to the concep¬ 
tion of the countermeasure index.-' Tests with 
animals had indicated that the internal air tem¬ 
perature was the factor which determined sur¬ 
vival within the tower. Therefore, the ratio of 
maximum air temperature to total heat input, 
when multiplied by 100,000, provided a con¬ 
venient index of countermeasure effectiveness. 


6.10.3 Experimental Conditions 

Coyming Tower. The conning tower was from 
a cruiser of the Wichita class (Figure 15) with 
an overall height of 16 ft, and the enclosed 
space was divided into two 8 ft high compart¬ 
ments by a horizontal plate. The top compart¬ 
ment, the conning tower itself, was constructed 
of class B armor plate and the compartment 





162 


MISCELLANEOUS ELAME WARFARE ITEMS 



Figure 15. Front view of conning tower from a 
cruiser of the Wichita class. 


below, of light steel. The tower was 14 ft in. 
through the long axis by 7 ft 5% in. through 
the short axis and had a total mass of 80,920 lb, 
corresponding to a total heat capacity of 8,920 
Btu/F. Figure 16 gives additional details on the 
construction of the tower. 

Fuel. Since the quantity of fuel deposited by 
a suicide plane would be difficult to predict, a 
standard amount of three 55-gal drums of gaso¬ 
line was used. These drums were placed in fixed 
positions on the upper passageway of the tower 
and were simultaneously split open and ignited 
by a charge of black powder and tetryl. 

Instrumentation. To measure the variables 
(1) wind velocity and direction, (2) humidity 
of outside and inside air, (3) temperature in 
walls, floor, and ceiling, (4) ambient air tem¬ 
perature in the tower, (5) radiant heat in the 
tower, (6) changes in atmospheric composition 
within the tower, and (7) outside air tempera¬ 
ture, the following instruments were used: (1) 
recording anemometer, (2) sling psychrometer 
and Foxboro recording psychrometer, (3) three 
iron constantan thermocouples connected to 
recording potentiometers, (4) gas analysis 
equipment and Cities Service heat prover for 
measuring oxygen concentration, and (5) ther¬ 
mometers. 

Test Animals. The test animals, young do¬ 
mestic pigs, were placed in stiff wire cages and 
hoisted by means of cables to any desired loca¬ 
tion within the towers. The cable system was so 


constructed that a person standing in the bottom 
of the hatchway could remove one or both of 
the animals at any time during an experiment. 

Spray and Fog Nozzles. Special nozzles were 
used to produce either a spray or a fog within 
the conning tower. The spray nozzles were 
capable of delivering approximately % gal of 
water per min when under 100 lb of pressure, 
and the fog nozzle delivered 2.5 and 3.4 gal of 
water per hr when under pressures of 50 and 
110 lb, respectively. 

Forced Ventilation. In some of the runs 
forced ventilation was provided through a 6-in. 
duct which terminated 2 ft below the deck of 
the conning tower. The air was supplied by a 
V 5 -hp fan located at the end of a 10-in. duct 
which was connected to the 6-in. line. The quan¬ 
tity of air was regulated by means of a damper 
placed in the line below the fan. The air passed 
out of the tower through a 10-in. duct in the 
roof. 

Insulation. In some of the runs the inside of 
the tower was insulated by blankets of glass 
wool 1 in. thick, fastened to the roof and walls. 
A 4-in. layer of glass wool was packed between 
the false floor and the deck. The hatchway was 
insulated with a 2-in. blanket of glass wool to 
provide protection against fires in the lower 
compartment. The blankets were held in place 
by stud bolts welded to the conning-tower walls. 


Results 

Port Plugs. The requirements for port plugs 
were that the plugs must be transparent, not 
decrease the angle of vision, be able to with¬ 
stand shock and intense fire, be able to seal the 
port completely, and be easily replaced. To 
meet these requirements, a laminated glass 
block (Figure 17) was tested and found to be 
satisfactory under the conditions of the tests. 
Although the heat severely cracked the outer 
layers of glass, impairing the vision, these plugs 
withstood repeated fires and sudden chilling. 
There was no leakage whatsoever and damaged 
plugs were easily replaced. 

Drainage. Referring to Figure 16, the possi¬ 
bility of large quantities of liquid accumulating 
in the top passageway can be seen. To minimize 










PROTECTION OF SHIP CONNING TOW EKS AGAINST SUICIDE PLANE ATTACK 163 




to warm tower as ambient air temperature was low. 

Its of fourtli drum emptied in lower compartment for fire below. 




































164 


MISCELLANEOUS FLAME ARFARE ITEMS 


the amount of fuel collected in the passageway, 
two 2-in. drain pipes were installed. Figure 18 
shows the material reduction in thermal effi¬ 
ciency that was accomplished by drainage. In 
addition to the drain pipes, slots were cut in 
the base of the splinter shield in the upper 
passageway. The slots, however, were effective 
only for a short period of time because of ex¬ 
cessive warping of the deck. 

Wind. The wind had a very pronounced effect 


flames would be directed over the sides of the 
ship and would make fire control easier. 

Spray and Fog Nozzles. In Table 2 there is 
given a complete summary of the effectiveness 
of the countermeasures as measured by the 
countermeasure index. Spray nozzles did not 
show any significant change in this index as 
compared to tests without spray nozzles. 

Similarly, fog nozzles did not prevent the in¬ 
terior temperature from rising. It is evident 



LOCATION OF THERMOCOUPLES 

1C- SOUTH WALL IN CONNING TOWER 
2C- NORTH WALL IN CONNING TOWER 
3D-ON FALSE FLOOR OF CONNING TOWER 
4T- ON UNDERSIDE OF ROOF OF CONNING TOWER 
5C- WEST WALL IN CONNING TOWER 
6C- EAST WALL IN CONNING TOWER N 

7AB- BRIGHT BODY SUSPENDED IN AIR t 

BAD- BLACK BODY SUSPENDED IN AIR / 


■ PEEPHOLES- 


DRAIN HOLES IN SPLINTER SHIELD (4) 
/-2 IN. ROOF 




— r 

^6 IN. ARMOUR 

V 

1 , 



o 

I5C 

K^fc 

6C 1 


1 

J 


12 IN.SILL AT 
ENTRANCE TO 
UPPER WALKWAY 


FALSE FLOOR 

2 IN.X8 IN. DRAINS 

^ 


IftIN.CONNING TOWER FLOOR 



I / "" 1 

' L 2 in^oECK DRAINS, 



LIGHT STEEL AIR TIGHT 
COMPARTMENT BELOW 
CONNING TOWER 


-ACCESS TO 
LOWER WALKWAY 


-GROUND LEVEL 



^—WATER TIGHT DOOR TO 
LOWER COMPARTMENT 

Figure 16. Diagrammatical views of conning tower showing experimental conditions. 


on the thermal efficiency. Referring again to 
Figure 18, the sharp decrease in thermal effi¬ 
ciency with increasing wind velocity will be 
noted. Since, however, the wind is not a con¬ 
trollable variable, advantage can only be taken 
by directing the ship into the wind. If the ship 
is free to maneuver, practical utilization of the 
wind would be to set the course of the ship 40 
to 50 degrees with the wind. In this way the 


that beside the discomfort incurred in a closed 
room filled with spray or fog there appeared to 
be no beneficial results from the use of nozzles. 

Ventilation. When tests were conducted using 
forced ventilation, considerable reduction in the 
index occurred. Using a rate of 740 ft per min, 
the index was reduced by 50 per cent (Table 2, 
runs 66 and 45). To further substantiate the 
effect of ventilation, the fan was alternately 


^fidentIal^ 





































































PROTECTION OF SHIP CONNING TOWERS AGAINST SUICIDE PLANE ATTACK 165 


turned on and off during one test. A tempera¬ 
ture rise and fall which corresponded with the 
fan off and on was noted. No evidence could be 
found that a combination of fog and ventilation 
possessed any advantage over ventilation used 
alone. 


GLASS PLUG-^ 



Figure 17. Sketch of glass plug for conning- 
tower peepholes showing plug in position. 

Insulation. Glass-wool insulation used inde¬ 
pendently had the same effect on the counter¬ 
measure index as forced ventilation. A compari¬ 



WIND VELOCITY MPH 

Figure 18. Effect of wind and damage on steel 
wall temperature rise. 


son of runs 73 and 45 shows about 50 per cent 
reduction in the index. The use of insulation and 
forced ventilation in combination produced the 
most favorable condition, as evidenced by com¬ 
paring runs 74 and 75 with either 66 or 73. 


|!ONFIDEN TIAL^ 

























































Chapter 7 

STUDIES ON FLAME-THROWER DESIGN 


INTRODUCTION 

T he value of a flame thrower depends upon 
(1) the distance that the fuel can be pro¬ 
jected, (2) the amount of burning fuel that can 
be placed on the target in a given time, (3) the 
burning rate of the fuel, and (4) the reliability 
of the weapon. 

The independent variables determining these 
performance characteristics may be divided 
into two classes: (1) the design variables, which 
include nozzle shape and size, nozzle flow con¬ 
trol, ignition mechanism, propulsion mecha¬ 
nism, and controls; (2) the operating variables, 
which include fuel composition and consistency, 
fuel pressure, gun elevation, composition and 
proportion of secondary fuel, wind direction 
and velocity, and temperature, some of which 
are controllable and some are not. 

Some of the factors of design, particularly 
those affecting ruggedness and general reliabil¬ 
ity of the weapon, are best appraised by actual 
battle experience or by field shakedown tests 
simulating or exaggerating battle conditions. 
Others are susceptible of evaluation only by 
careful laboratory or field tests under repro¬ 
ducible conditions. The present chapter presents 
results of studies of factors of the latter type. 

Next to reliability the range of a flame 
thrower is its most important characteristic. 
Unfortunately, the term has been used too 
casually. In the assessment of two different 
flame throwers by two different groups a small 
difference in the choice of angle of elevation, 
wind velocity, or fuel consistency can com¬ 
pletely mask a real, and perhaps important, 
difference in the range of the weapons. In this 
chapter the term range will refer to the distance 
to the center of ground deposit of the fuel, and 
pertinent operating conditions will be specified. 

The material for this chapter is drawn from 
the work of all NDRC contractors on flame 
throwers. This group includes, in chronological 
order of initiation of work, Massachusetts In¬ 
stitute of Technology, Factory Mutual Research 
Corp., Standard Oil Development Co., Eastman 


Kodak Co., E. I. du Pont de Nemours & Co. 
(Section 11.2), Standard Oil Co. (Indiana), 
Shell Development Co., C. F. Braun & Co., Mor¬ 
gan Construction Co. and State University of 
Iowa. Also, it has been necessary to refer occa¬ 
sionally to the parallel work of the British and 
Canadians, but no attempt has been made to 
present their results in detail. 


■ 2 NOZZLE DESIGN 

Introduction. It is generally recognized that 
the range and physical characteristics of fluid 
jets are influenced, to some degree, by the 
nozzle design. The exact portion of a flame 
thrower designated by the term nozzle is a 
matter of definition; the term will refer here 
to that section which reduces the flow from a 
large cylinder to an orifice, or, in general, to the 
last mechanical section prior to the discharge 
of the jet from the apparatus. In several of the 
designs the situation will be somewhat compli¬ 
cated by the addition of secondary fuel at the 
point of contraction. Also, both pintle valves and 
straight-section extensions will be considered 
a part of the nozzle. 

Newtonian Liquids. Early work, as might be 
expected, was based on Newtonian fluids. Non- 
Newtonian fluids were included later when 
their utility as flame-thrower fuels was recog¬ 
nized. Preliminary experiments with high-speed 
photography on a nozzle converging in diameter 
from 4Z) to D formed by a part-circle revolution 
(radius = 13D), followed by a straight section 
6D long, showed an early breakup of the jet.^ 
The use of a straight section was considered 
not only unnecessary, but even a possible source 
of turbulence generated in the liquid; and for 
this reason straight sections were early aban¬ 
doned on experimental models. 

Previous studies by the British, as reported 
in a conference on flame throwers held March 
3, 1942, indicated that there was little differ¬ 
ence in the ranges obtained from nozzles of 
varying designs having the same vena con- 


rOTKF lDENTIAL") 


166 




NOZZLE DESIGN 


167 


tracta.- These conclusions were substantiated 
by the work of Factory Mutual Research Corp., 
which tested three nozzles having included 
angles of 15, 37, and 90 degrees. When the 
nozzle diameters were adjusted to give equal 
discharge at equal pressure, the results showed 
no effect of rate of contraction on the range of 
the jet.^ On the basis of these findings and 
those of Shell Development Co. on high-pressure 
hydraulic nozzles, it was concluded that the 
possibility of a further increase in the range 
from improved nozzle design was small in com¬ 
parison to the increase that might be expected 
from changing some of the other variables. The 
emphasis, therefore, was shifted to the other 
variables.^ 

Non-Neivto7iian Liquids. Initially the nozzles 
for Newtonian fluids were used in the study of 
non-Newtonian fluids. However, British experi¬ 
ments with high-speed photography on various 
nozzle designs and using FRAS (aluminum 
stearate-thickened fuel) showed that the addi¬ 
tion to the nozzle of a straight section of several 
nozzle diameters reduced jet breakup."’ 

Since the range is dependent upon jet 
breakup, it was concluded that the addition of a 
straight section should give an increased range. 
Experiments by the NDRC groups at MIT 
and Standard Oil Co. (Indiana) confirmed this 
conclusion.®’ ‘ Figure 1 illustrates the increased 
range obtained by the addition of a straight 
section to the nozzle. It will be noted that the 
per cent increase in range is somewhat greater 
for the smaller-sized nozzles. In addition, 
there appears to be an optimum length for 
the straight-section extension. This has been 
thought to take care of a period of relaxation 
after the jet is accelerated through the nozzle 
with attendant deformation of the gel.^ Shell 
Development Co. found that extremely long ex¬ 
tensions of 3 to 5 ft did not only fail to improve 
the range but impaired the ignition.® However, 
more recent studies by Standard Oil Develop¬ 
ment Co. do not appear to agree with the earlier 
findings on maximum extensions; they have 
found that an extension of several feet definitely 
improves the performance. 

hitroduction of Secondary Fuel mto Nozzle. 
Regardless of the performance of an unignited 
jet, it must always be remembered that for best 


flame-thrower performance complete ignition of 
the jet is essential. To accomplish this, the prin¬ 
ciple of secondary fuel addition was introduced 
(see “Secondary Fuel and Pintle Valve”). Sev¬ 
eral nozzles were designed which introduced 
the secondary fuel on the periphery of the main 



Figure 1. Effect of nozzle design on range. 


gel rod at the point of contraction® while others 
introduced the secondary fuel in a section pre¬ 
ceding the nozzle. 

In type A (Figure 2A) the secondary fuel 
entered the main stream near the beginning of 
the contraction and, therefore, the mixture of 
thickened fuel and gasoline contracted together. 
In all probability a venturi effect was estab¬ 
lished but not to any great extent, since in 
operation it was necessary to maintain the sec¬ 
ondary fuel at a higher pressure than the main 
fuel. Because of the difficulty with reproducibil¬ 
ity of results from nozzle A, a new nozzle, type 
C, was designed (Figure 2B), in which the sec¬ 
ondary fuel was introduced after the main jet 
had contracted. In this way the secondary fuel 
was applied in a very thin film. With momentum 
transfer increased, the required secondary fuel 
pressure could be reduced. Type C proved to be 
much easier to adjust than type A, possibly 
through the reduction of disturbances which 
might have been set up during the contraction 
of the mixed jet. In an effort to maximize the 
venturi effect, a nozzle was designed in which 


CONFIDENTljOT} 












168 


STUDIES ON FLAME-THROWER DESIGN 


(L 

I 




type A. 

Figure 2B. Nozzle for 1.2-gal flame thrower, 
type C. 


the gel stream expanded after the point where 
the secondary fuel was introduced. Although 
the venturi effect was increased considerably, 
the nozzle was much too sensitive to adjust. 
Since no comparative tests have been made, no 
conclusions can be drawn on the relative per¬ 
formance of the Indiana nozzle with others. 

Secondary Ftiel and Pintle Valve. Introduc¬ 
tion of secondary fuel in the annulus of a nozzle 
fitted with a pintle valve gave rise to further 
complications. A spring-operated pintle valve 
was designed with the purpose in mind that the 
fuel flowing through the nozzle when the pintle 
was open would accelerate at a constant rate. 
To accomplish this, the convergent section of 
the nozzle had the same curvature as the pintle. 
The secondary fuel for this nozzle was intro¬ 
duced through an annular opening upstream 
from the straight section. Insufficient tests of 
this type of design prevented a true evaluation 
of the nozzle. 

A similarly designed nozzle was developed and 
tested by another group.It was stated that in 
this nozzle the secondary fuel did not reach the 
same velocity as the main gel stream and, con¬ 
sequently, burned off too rapidly. In order to 
prevent this premature burning a venturi 
throat was inserted ahead of the pintle valve. 
The secondary fuel remained on the rod longer, 
but the rod appeared to have greater breakup. 
Further experiments indicated that the opti¬ 
mum point for admission of the secondary fuel 
was in the convergence just back of the point 
where the pintle piston seats. 

Nozzle Smoothness. The character of the jet 
periphery, in part determined by the nozzle 
smoothness, affects the range by controlling the 
degree of ignition. In the instances where no 
secondary fuel is used ignition becomes more 
difficult with increasing fuel consistency and, 
over the range of practical interest, with nozzle 
pressure. If a roughly machined nozzle is used, 
the slight surface disturbance created on the jet 
makes it possible for a flame to remain on the 
jet," whereas there is a tendency for the flame 
to blow out on very smooth jets. Thus one con¬ 
cludes that under conditions of absence of igni¬ 
tion trouble, such as warm weather and thin 
fuel, a smooth nozzle is desirable to minimize jet 
breakup; but if ignition is controlling, a rough 
nozzle is better. 


\ confidentiai7^ 















































EFFECT OF APPROACH CONDITIONS 


169 


Pmtle Valve. The introduction of the pintle- 
valve principle for flame throwers would seem 
to lead to a possible disturbance in the jet. This 
fact was demonstrated in the high-speed photo¬ 
graphic work by the British."* However, they 
also showed that the straight-section extension 
eliminated any visible disturbance at the nozzle. 
The effects of the pintle valve on breakup and 
range have never been adequately studied, al¬ 
though there is some evidence, from work at 
Edgewood Arsenal, that the pintle valve has 
some effect on the jet (see section on Effect of 
Approach Conditions) 

Nozzle Diameter. As will be shown later in 
the section on Correlation of Range Data, in¬ 
creasing the jet diameter reduces the tendency 
for the jet to break up and, therefore, increases 
the range (Figure 3). However, the rate of in- 



JET VELOCITY FT/SEC 

Figure 3. Effect of nozzle diameter and velocity 
on range. 

crease of the range with increased diameter is 
much less for larger nozzles. An additional im¬ 
portant consequence of increased diameter is 
the increased fuel-discharge rate. Consequently, 
the extent to which the diameter can be in¬ 
creased depends largely upon the fuel capacity 
of the flame thrower. 

- a EFFECT OF APPROACH CONDITIONS 

hitroduction. The approach to the nozzle ex¬ 
erts several effects upon the range of a flame 


thrower. First, pressure losses between the 
fuel supply and nozzle due to friction are com¬ 
mon to both thickened and unthickened fuels. 
Second, turbulence in the issuing jet is associ¬ 
ated primarily with Newtonian liquids, and 
consequently is of reduced interest in modern 
flame-thrower design. A third is “gel working.” 
Although data available on this last phenome¬ 
non are very limited, evidence exists that vari¬ 
ous obstructions cause the gel to undergo 
internal changes which cause an early breakup 
of the jet, with consequent reduction of range. 

Valves. A specific example of gel working 
caused by approach conditions was studied by 
the Eastman Kodak group.Using high-speed 
photographic technique, they observed the char¬ 
acteristics of the stream issuing from the down¬ 
stream side of a ball valve and Y valve, such as 
used in different models of an MlAl flame 
thrower (Figure 4). Similarly, they observed 
the jet from an MlAl flame thrower, first pro¬ 
vided with a Y valve, then with a ball valve, and 
also compared these to an M2-2 flame thrower 
having a pintle valve. In all cases for two pres¬ 
sures and two types of gels, the photographs of 
the jets showed a greater disturbance for the 
Y valve than for either the ball or pintle valve. 
The pintle valve performance appeared to lie 
between the other two valves. 

The range data for ignited jets were con¬ 
sistent with the results of the photographs of 
the unignited jets. The ball and pintle valve 
gave substantially greater ranges than the Y 
valve (Table 1). 

Disturbance in Fuel Line. In an attempt to 
determine the effect on the range of obstruc¬ 
tions in the line, cylindrical and multiple ex¬ 
pansion-contraction plugs were inserted prior 
to a straight section leading to the nozzle.In 
Figure 5, Section E illustrates the type of plug 
used. The plugs were held in place by supports 
which had slits 22 nozzle areas in cross section 
to allow for the passage of the fuel. The annular 
cross section was equivalent to 15 nozzle areas 
for the cylindrical plug and varied from 15 to 
20 for the multiple expansion-contraction plugs. 
Careful measurement of range disclosed that 
these disturbances did not appear to have any 
consistent effect whatsoever on the range. 

Straight Sections. Some effects of straight 



















170 


STUDIES ON FLAME-THROWER DESIGN 


4.2 7o IMPERIAL NR-651, WARM I DAY , COLD 3 DAYS (FIRED COLD) 
GARDNER CONSISTENCY 300 



MIAI GUN WITH BALL VALVE (250 PSD MIAI GUN WITH Y VALVE (250 PSD 



M2-2 GUN (PINTLE VALVE) 250 PSI 


4.27o IMPERIAL NR-651, WARM 4 DAYS 



MIAI BALL VALVE ALONE (100 PSI) 



MIAI GUN WITH BALL VALVE (250 PSI) 



M2-2 GUN (PINTLE 


Figure 4. Breakup of thickened fuels 

sections have been observed.'-^ Figure 6 shows 
that a long, narrow approach gives a somewhat 
greater range than a short wide section. It is 
possible that in the long section the gel mole¬ 
cules become better aligned than they do in the 
shorter section, and the gel structure is less 


FIRED WARM) GARDNER CONSISTENCY 100 



MIAI Y VALVE ALONE (100 PSI) 



MIAI GUN WITH Y VALVE (250 PSI) 


VALVE ) 250 PSI 

in flame-thrower valves and nozzles. 

subjected to further deformation in the con¬ 
traction from 14 ill- to Vs in. than in the 1 -in. 
to Vs-iii- contraction. The lower per cent gels 
give no evidence of increase in the range under 
the same conditions. 

Bends. Tests on other types of obstructions 







EFFECT OF APPROACH CONDITIONS 


171 


substantiated the gel working theory. Figure 7 
shows the effect of gel viscosity on the range for 
two nozzle sizes. A pair of acute bends, acute 
bends plus a mock pintle, a pair of smooth bends 

Table 1. Comparison of MlAl gun with ball and Y 
valves with M2-2 gun fired from E5R1 fuel tanks, 250 psi. 


Gardner 
consist¬ 
ency at 
Temper- temper- 


ature 

ature 



Flame 

Range 

when 

when 



diam¬ 

(center of 

fired 

fired 

Gun 

X'alve 

eter 

deposit) 

(Fj 

(g) 



(ft) 

(yd) 


26 

250 

Ml.Al 

Y 

1.8 

48 

26 

250 

MlAl 

Ball 

0.8 

54 

26 

250 

IM2-2 


1.3 

54 

26 

250 

MlAl 

Y 

0.6 

48 

26 

250 

MlAl 

Ball 

0.6 

52 

30 

300 

MlAl 

Y 

1.1 

43 

30 

300 

MlAl 

Ball 

0.5 

61 

30 

300 

M2-2 


0.9 

51 

70 

100 

MlAl 

Y 

2.0 

45 

70 

100 

MlAl 

Ball 

0.6 

65 

70 

100 

M2-2 


1.5 

60 

32 

210 

MlAl 


1.8 

43 

32 

210 

MlAl 

Ball 

1.0 

58 


(tube turns) and a dwarf pintle valve set in a 
straight section of pipe gave up to 20 per cent 
reduction in the range for the %-in. nozzle.^ 


The smooth bends caused the greatest reduc¬ 
tion in range. These results are interesting 
when compared with friction losses, in which 
sharp bends and obstructions give greater pres¬ 
sure losses than smooth bends. A possible ex¬ 
planation for the reduced range of thickened 



NOZZLE VELOCITY IN FT/SEC 

Figure 6. Comparison of effects of short 1-in. and 
long 14-in. straight sections on range of 7.8 per 
cent Napalm gels, unignited, issuing from a 
%-in. nozzle. 

liquids after passing through smooth bends is 
that the gel stream has time to become de¬ 
formed and turbulent, or to produce an inside 
fold. On the other hand, when the gel stream 
passes through a sharp bend, there is not suffi¬ 
cient time for permanent deformation to take 
place, the elastic forces in the gel causing a 
return to its original structure (see Chapter 8). 

It will be noted that the i/4-in. nozzle gave 
almost no variation in the range due to ob- 



rABL£ OF LENGTHS CO OF 
INNER WALLS (INCHES) 


INNER WALL DIAMETERS 

(Cl 

!// 



SHORT 

C 

3.58" 

B 

3 00" 

D 

2 25" 

MEDIUM 

G 

7.14“ 

F 

6 76“ 

E 

6 O!" 

LONG 

K 

14 67" 

J 

14 29“ 

H 

13 S4" 


SECTION E (I’MEDIUM ) WAS USED WITH AND 
WITHOUT THE FOLLOWING OBSTRUCTIONS 



NOTE 0 25 050 LOO 



CYLINDRICAL PLUG 
DIA - (/a 
LENGTH - 5" 


MULTIPLE EXPANSION-CONTRACTION 
PLUG, MIN DIA = 3/e' 

MAX DIA - V 
LENGTH = 5" 


Figure o. Diagrammatic sketches of MIT %-in. nozzle with various types of approach sections. 


confIMntial 







































































































DISTANCE 10 CENTER OF DEPOSIT IN TARDS 


172 


STUDIES ON FLAME-THROWER DESIGN 


striictions, except for smooth bends. This was made on this effect other than to note that there 

possibly because of the much lower velocity in appeared to be no significant decrease in the 

the i/4-in. apparatus. These results on bends range, 
have been confirmed by other investigators.^^ 
















=FfflTTT 















1 1 1 1 1 1 1 

TYPE OF 

— STRUCTURE USED 

BEFORE NOZZLE 





























[ONORMAL NOZZLE 

X SHARP RIGHT ANGLE TURNS 

° 

71 












0 75‘VA SHARP RIGHT ANGLE TURNS 

1 PLUS LARGE PINTLE 

k). ^ LJ or-aunc-Ti IQC TllOKlQ” 













— 1 

— 

•s..-Oi’nvu 1 n iwiub. p 

[□DWARF PINTLE 















1, 

•NORMAL NOZZLE 

3- 













QSMUUIM lUOt lunno 

0.25’XaSHARP RIGHT ANGLE TURNS 
PLUS LARGE PINTLE 
(Sdwarf pintle 

-/ 













» - 













1 1 1 1 M 1 1 


°0 2 4 6 8 10 12 14 16 IS 20 22 24 26 28 30 32 34 36 38 40 


VISCOSITY OF FUEL IN 10^ POISES 

Figure 7. Relation between gel disturbance and 

range. 

However, the lack of sufficient data prohibits 
any definite conclusions to be made on the exact 
effect of gel working 

Pumps cmd Water Hammer. In a study of 
pump propulsion, the Eastman Kodak group ob¬ 
served that the pump-propelled jet was broken 
up a short distance from the nozzle, while the 
compressed-gas propelled jet remained intact 
at similar distances (Figure 8).^^ By using a 
piezoelectric crystal pickup, the pressure oscil¬ 
lations caused by the pump were measured. 
However, the oscillations were found to be sub¬ 
stantially reduced by placing a surge chamber 
consisting of a synthetic rubber bag in a 3-in. 
perforated tube inclosed in a 4-in. pipe. As the 
gel flowed through the annular space between 
the outer shell and the bag, which was pre- 
loaded to a pressure lower than the operating 
pressure, the pressure oscillations were ab¬ 
sorbed by the rubber bag. 

During a study at Edgewood Arsenal of the 
“water hammer” effect in the E13R2 flame gun, 
the piezoelectric crystal pickup showed a pres¬ 
sure fluctuation during the entire burst.Since 
the oscillations persisted throughout the burst, 
it seems likely that the phenomenon is a steady 
effect rather than a transitional one (Figure 9). 
Again these oscillations were reduced by intro¬ 
ducing a surge chamber upstream from the 
pintle valve. No further investigations were 


' ^ PRESSURE LOSSES IN PROPULSION 
SYSTEMS 

Introduction. In a flame thrower the magni¬ 
tude of the pressure of the fluid at the nozzle is 
one of the major factors governing the range. 
Any pressure loss that occurs from the fuel tank 
to the nozzle reduces the effective pressure and, 
therefore, the efficiency of the flame thrower. 
For the portable flame thrower the pressure loss 
has been shown to be approximately 55 per cent 
of the fuel-tank pressure for MlAl and 30 
per cent for M2-2.i'’ For tank-mounted flame 
throwers and other systems in which the dis¬ 
tance to the nozzle is considerably more and the 
path more complicated the pressure losses be¬ 
come even more significant. In the design of 
early apparatus to be used with unthickened 
fuels sufficient data existed to make rough esti¬ 
mates of pressure losses. With the introduction 
of thickened fuel, the viscosity of which was a 
function of the rate of shear, no information 
was available to make comparable predictions. 
A limited amount of data on the flow of thick¬ 
ened fuels has been collected since then to per¬ 
mit a fair correlation of the various operating 
variables with the pressure drop. 

Pressure Loss in Straight Pipes. A number 
of groups have measured the pressure losses in 
sections of straight pipe.“’ Since the 

thickened fuels are non-Newtonian, the analysis 
of the flow becomes complicated, but a correla¬ 
tion has been found in the viscous flow region. 
If Q/D^ (proportional to shear rate) is plotted 
against D (^P) /4L (shear intensity at the pipe 
wall) on logarithmic paper, a straight line is 
obtained at the lower flow rates (see “Nomen¬ 
clature” at the end of this chapter). For the 
same gel the flow curve is independent of the 
pipe diameter over a considerable range, as 
illustrated by the curves at left in Figure 11. In 
order to represent all the data for various gel 
strengths, an empirical relation has been de¬ 
termined involving the factor Z)(AP)/L di¬ 
vided by Gardner number +40.^^ Figure 10 



































PRESSURE LOSSES IN PROPULSION SYSTEMS 


173 


HALE GEAR PUMP - UNIGNITED JET GOBS 2 FT APART 




BLACKMER BUCKET PUMP-UNIGNITED JET GOBS 4-5 FT APART 





24-27 FT FROM NOZZLE 
GRANCO KNUCKLE PUMP - UNIGNI TED JET GOBS 8-9 FT APART 




10-13 FT FROM NOZZLE 


24-27 FT FROM NOZZLE 


REGULAR M2-2 FUEL TANKS AND PRESSURE BOTTLE 
UNIGNITED JET IGNITED JET 




24-27 FT FROM NOZZLE 
GRANCO KNUCKLE PUMP - IGNITED JET 



24-27 FT FROM NOZZLE 24-27 FT FROM NOZZLE 

LARGE GOBS CARRY FLAME THIN STREAM BETWEEN GOBS LARGELY UNIGNITED 


Figure 8. Single frames from high-speed (2,500 frames-sec) movies of jets of thickened fuels propelled 
by pumps. 





















































174 


STUDIES ON FLAME-THROWER DESIGN 



FLAME 

THROWER 

YARDS 

FROM 

NOZZLE 

IGNITED 

SECONDARY 

FUEL 

SURGE 

CHAMBER 









MIT 

2-4 

NO 

NO 

NO 







-- 

MIT 

2-4 

NO 

YES 

NO 


> 

MIT 

2-4 

NO 

YES 

YES 








MIT 

10-12 

NO 

YES 

NO 



MIT 

10-12 

NO 

YES 

YES 








MIT 

10-12 

YES 

YES 

NO 


SOD 

2-4 

NO 

NO 

NO 

) 

SOD 

2-4 

NO 

YES 

NO 



SOD 

10-12 

NO 

YES 

NO 


Figure 9. Prints from high-speed movies of MIT and SOD flame-thrower jets, with 400 Gardner fuel, %-in. 
nozzles, and 400-psi regulator set pressure in every case. All movies taken at 3,000 to 3,200 frames/sec. 


gpNFIDENTIAi?! 





































PRESSURE LOSSES IN PROPULSION SYSTEMS 


175 


shows the curve resulting from plotting this 
new factor against Q/D'\ utilizing data on four 
pipe sizes and three Gardner consistencies. To 
test this relationship, the data from another 
groups® were used in the same correlation. For 
the limited data at disposal it appears that 
Figure 10 represents the best available correla¬ 
tion on pressure drop in straight sections of 
pipe at flow rates up to 10, 60, and 120 gal per 


flow rates the curve for a 2.5 per cent Napalm 
solution is a continuation of that obtained fol¬ 
lower flow rates (Figure 11, bottom curve). 
However, it is probable that, if additional con¬ 
centrations and pipe sizes were studied, the 
curve would branch out into a family of curves 
at these higher flow rates in such a manner as 
characterizes the group of curves shown for 
Newtonian liquids. 



0 / 0 ^ 


NOTATION 


LEGEND 



EXPERIMENTAL RANGES 

0=FLOW RATE IN US GALLONS/MINUTE 



DIAMETER 

Q - 0 TO 75 

D=PIPE DIAMETER IN INCHES 


'/2 

■•V 

l" 

l'/2' 2” 

D - '/2 TO 2 

P=PRESSURE IN POUNOS/SQUARE INCH 

GARDNER 

no 0 


A 

□ 

G - no TO 850 

L= PIPE LENGTH IN FEET 

" 

390 • 


A 

■ 

IMPERIAL NAPALM BATCH 2255 

G= GARDNER CONSISTENCY IN GRAMS 

■■ 

850 . 


+ 

X 



EASTMAN 

88-485 

0 


0 



Figure 10. Flow of Napalm gels in pipes. Generalized curve. 


min in 1-in., and 2-in. pipes, respectively. 

Few data exist for higher rates of flow. A 
comparison of Figure 10 with the known per¬ 
formance of Newtonian liquids in pipes sug¬ 
gested that at high or intermediate flow rates 
diluted Napalms should show lower pressure 
loss on pumping than straight gasoline. Ac¬ 
cordingly, a limited amount of data at higher 
flow rates was obtained. Figure 11, right-hand 
side, shows the pressure loss for gasoline and 
2.5 per cent Napalm at these higher rates. It 
can be seen that at equal flow rates the pressure 
loss is less for the thickened fuel than for gaso¬ 
line. This unusual circumstance has been at¬ 
tributed to the fact that in the region of tur¬ 
bulent flow under identical operation conditions, 
the degree of turbulence for the Napalm solu¬ 
tion is less than for gasoline. 

The data show that in the region of higher 


Pressure Losses in Pipe Fittings. The pres¬ 
sure loss of thickened liquids in valves, bends, 
and most other fittings has not been reported. 
A few experiments were made on the effect of 
a contraction in the line.^® In this work 3 per 
cent Napalm gel was pumped into a %-in. pipe 
(reduction in diameter 1 / 2 ) and into a Vw-’m. 
pipe (reduction in diameter Vs)- Figure 12 
shows the pressure plotted against the distance 
from the contraction. For these conditions the 
pressure loss up to 40 in. from the point of con¬ 
traction was not a linear function of the length 
as was the case beyond 40 in. downstream. By 
extrapolating the linear portion of the curve 
backwards to zero length, an uncorrected con¬ 
traction loss of 6.4 psi for a %-in. to %-in. re¬ 
duction and 2.9 psi for a lV2-ii"i- to %-in. 
reduction was obtained, using a 3 per cent 
Napalm gel. 












































176 


STUDIES ON FLAME-THRO\^ ER DESIGN 



0.1 0.5 1 5 10 50 100 500 1000 4000 


Q_ GAl/MIN 
05 IN.3 

Figure 11. Flow characteristics of Napalm solutions in gasoline. 


The imcorrected contraction loss is the sum 
of the increase in kinetic energy of the stream 
and the corrected contraction loss. The kinetic 
energy of a plastic stream is dependent upon 



Figure 12. Pressure drop in pipe following reduc¬ 
tion in cross section for a 3 per cent Napalm gel. 


the velocity (average) and the extent of plug 
flow (c) and varies from piXn'Y/g when r = 0 to 
pL{u')-l2g when r=l. Hence, if the constants of 
the plastic material are known so that the extent 
of plug flow (c) before and after contraction 


can be estimated, it is possible to compute the 
kinetic energy change accompanying the con¬ 
traction. Subtraction of the increase in kinetic 
energy from the observed total contraction loss 
gives the corrected contraction loss. 

Nozzle Discharge Coefficients. The mechani¬ 
cal energy loss in a nozzle as expressed by the 
discharge coefficient has been studied quite ex¬ 
tensively for Newtonian fluids. In order to com¬ 
pare the discharge coefficients of Newtonian 
and non-Newtonian fluids, an investigation of 
several gel strengths was made on different 
nozzles.Although the Gardners of the various 
gels were not determined, their strengths varied 
from 6 to 9 per cent Napalm. Basing the cal¬ 
culations on the formula^*^ 


1-25 (2 
^~p V 


(1) 


a series of coefficients for four nozzles was ob¬ 
tained over a range of pressure up to 240 psi. 
The results for a nozzle are shown in 

Figure 13 along with the curve for the coeffi¬ 
cient of discharge for water. Whereas the coeffi¬ 
cient of discharge for water does not vary with 
the pressure down to fairly low pressures, for 
values below 120 psi the coefficient for the gel 


yUWFlDENTIAL^ 














































































































































OPERATING VARIABLES 


177 


becomes a function of the pressure within that 
range. 

Subsequent work partially confirms these re- 
sults.^=^ Figure 14 shows results on a Va-in. 
nozzle, using different fuel consistencies and 


1.00 
0.90 
0.80 
0.70 

0.60 
0.50 
0.40 
0.30 
0.20 
0.10 
0 

0 20 40 60 80 100 120 140 160 ISO 200 220 

NOZZLE PRESSURE (PSD 







VSTE 

5- 












A 

n ° 



■ f 







J 










NAPAI 

-M G£ 

J 




/ 

r 





























































■»7.5 

7. SO 

SOAF 

'/.SOA 

AP 8/ 

’ CHE( 

P BAL 

\\.L 1 

:k te 

L TES 

■EST( 

fsA, 

LL)4< 

3 SEC 

50 F 




» =9.1* 

IT 82( 

3 SEC 

35 F 
















COEFFICIENT OF DISCHARGE 
WITH 8% NAPALM GEL 
NOZZLE FROM Ml FLAME THROWER 


Figure 1.3. Coefficient of discharge of nozzle from 
Ml flame thrower. 


approach sections. However, the values plotted 
are overall coeffitients which include the fuel 
piston, fuel cylinder, approach section, and 
nozzle. The nozzle coefficient itself probably 
corresponds to curves drawn through the tops 
of the groups of data for the three fuels used. 

An attempt was made to bring the curves of 
discharge coefficients onto a common curve by 
plotting discharge coefficient versus a Reynolds 
number evaluated from the Gardner consistency 
by the formula 


f, = k(G-6) ( 2 ) 


In consequence, the curves reversed their rela¬ 
tive positions and were actually more separated 
than without the viscosity allowance. 

Another approach was tried by assuming that 
the apparent or effective viscosity q for Napalm 
is given by the relation 


which leads to the conclusion that the Reynolds 
number is approximately proportional to 

and consequently, the discharge coefficient may 
be plotted versus 

£)a-k)/(i-\-k) p i/i+A- 


If k is assumed to have a mean value of 0.7, the 
above reduces to 


As shown in Figure 15, the curves again become 
reversed, indicating that there is still an over¬ 
correction. 


OPERATING VARIABLES 

Fuel Consistency. Fuel consistency is an im¬ 
portant factor in determining the range of a 
flame thrower; it is this property which has 
given the additional range that thickened fuels 
have over unthickened fuels. In addition, for 
both unthickened and thickened fuels the spe¬ 
cific gravity affects the range,-*^ but to a much 
less degree than consistency affects it. 

The many factors that determine the con¬ 
sistency of a gasoline gel are discussed in Chap¬ 
ter 8. In Figure 16 is shown the dependency of 
the range on the Gardner consistency. The solid 
curves of perfect ignition show the increase in 
range with increasing gel consistency. Within 
the limits of the data no optimum consistency is 
attained, provided perfect ignition is main¬ 
tained by means of secondary fuel. However, in 
practice the upper limit of gel strength is 
limited by supply of thickener and the mixing 
difficulties that occur at the higher concentra¬ 
tions. 

Certain thickened fuels will have identical 
Gardner consistencies, but will differ in their 
relative “shortness.” Several investigators have 
shown that the shortness of the gel does affect 
the jet characteristics-^'and in some in¬ 
stances the range for a “long” gel is 10 to 20 




(3) 
















































STUDIES ON FLAME-THROWER DESIGN 


8 




o 

in 

o 

in 

o 

m 

o 

in 

o 

in 

o 

in 

o 

in 

CT> 

(T> 

00 

CO 

t^ 

1^ 

CD 

CD 

m 

in 

•It 


tn 

ro 

cvj 

6 

d 

d 

d 

d 

d 

d 

d 

d 

d 

d 

d 

d 

d 

d 


lN3l0IJd300 39yVH0Sia 


Tco nfiMntial ) 


100 120 140 160 180 200 220 240 260 280 300 320 340 360 

NOZZLE VELOCITY IN EPS 
Figure 14. Discharge coefficient versus nozzle velocity. 



















































































































OPERATING VARIABLES 


179 


per cent greater than for a “short” gel. How¬ 
ever, it has been found that this effect of gel 
shortness on the range does not occur over a 
minimum of about i/o in. measured on the ex- 



01 2345 6789 10 II 


_u_ 

Figure 15. Discharge coefficient versus 

tensionmeter apparatus of Eastman Kodak.^^ 
Later work at Suffield on peptized fuels that 
have the same Gardner consistencies as un¬ 
peptized fuel showed no appreciable difference 
in range. 


has been made from high-speed photographs 
(Figure 17).-'^ The distance a low-velocity jet 
will travel before breakup depends primarily on 
the nozzle diameter, surface tension, and viscos¬ 
ity. As the velocity increases, the jet takes the 
form of a wave resembling that in a whipped 
rope. The whipping action in the jet reduces the 
distance that the jet travels before breakup and 
hence decreases the range. By increasing the 
pressure at the nozzle, a critical velocity of the 
fluid is reached beyond which atomization oc¬ 
curs. This is readily observed in Newtonian 
liquids, but less frequently in thickened liquids 
which have much higher critical velocities. 

Within the limits of practical operating pres¬ 
sures of flame throwers so far developed, it has 
been shown that the curve of range versus 
nozzle pressure is relatively horizontal at the 
optimum pressure.-^ Thus, considerable varia¬ 
tion of the operating pressure will have only a 
slight effect upon the mean range, though the 
dispersion of fuel on the ground may materially 
change. 

In addition to imparting velocity to a jet, the 
pressure affects the degree of ignition of a jet. 



Gel Consistency: Groms Gardner 

Figure 16. Effect of gel consistency on the range. 


Nozzle Pressure. Referring again to Figure 3, 
the effect of nozzle pressure and of nozzle 
velocity upon the range is evident. For a given 
nozzle diameter there is an optimum nozzle 
pressure above which the range decreases. An 
analysis of a jet under varying nozzle pressures 


In Figure 18 the actual range with imperfect 
ignition is plotted against the jet velocity, along 
with the theoretical range attainable with good 
ignition. At a low velocity of 150 ft per sec or 
less complete ignition is obtained, but as the 
velocity increases there is a tendency for the 


^NFIDENT!Ar ;i 





































PRESSURE IN PSI 


180 


STUDIES (U\ FLAME-TIIHOWEK DESIGN 


'/q" nozzle 



Figure 17. The breakup of jets of Napalm gels of various concentrations. 


l[CO NFIDENTIAir~l 






























PRESSURE IN PSI 


OPERATING VARIABLES 


181 




500 


707 


1.5 7o 


NAPALM 


3 % 


707 


Figure 17. {Continued.) 


250 


500 


'/4" NOZZLE 


UJ 

q: 

w 250 

UJ 

£E 

Ql 


■confidential} 















182 


STUDIES ON FLAME-THROWER DESIGN 


flame to blow out. As long as the jet remains 
smooth, the blow-out tendency continues to in¬ 
crease, and the range is reduced. However, a 
velocity is finally reached where the jet no 
longer remains smooth, and consequently there 
is an opportunity for the flame to remain on the 
jet. If secondary fuel is used, good ignition is 
maintained on the rod at all times. 


the maximum range occurs at an angle of eleva¬ 
tion somewhere between 20 and 30 degrees, but 
for larger jets the optimum angle of elevation 
is 15 to 20 degrees,-*^ 

Using the same analysis which appears be¬ 
low in the section on wind, it can be shown that 
the effect of wind on the range is a function 
of the angle of elevation, particularly when 



0 100 200 300 400 

Jet Velocity: Ft per sec 

Figure 18. Example of a condition in which ignition depends on jet velocity. 


Gun Elevation. In still air the range of a jet, 
like that of any projectile, is a function of the 
elevation. Theoretical calculations have been 
made of the effect of elevation on the range, 
and they are in close agreement with experi¬ 
mental results for elevations under an angle of 
15 degrees. At elevations above an angle of 15 
degrees considerable differences are noted be¬ 
tween the calculated and observed ranges. Ex¬ 
perimental data show that for jets up to in. 


shooting into a head wind. In the case of an 
ignited jet firing into a head wind, the com¬ 
ponent of the wind normal to the jet is low at 
low angles of elevation, and therefore the hot 
gas envelope which accounts for the greater 
range of an ignited jet is only slightly affected. 
At higher angles of elevation the wind com¬ 
ponent normal to the jet is increased, the hot 
gas envelope tends to be more completely blown 
off, and the range is decreased. 
















OPERATING VARIABLES 


183 


With increased wind velocity the above effect 
at higher elevations becomes so large that the 
reduction in the range due to the wind is greater 
than the gain in the range due to the greater 
angle of elevation (Figure 19). Consequently, 


:TVT 

--q— ' -1 

- -1 

! ^ 




II-1 

I 





A. ntAuwinu 

7 MPH; 





-- - —■ 


V 

o 

* 



— 





— 

1- 










-B. CROSSWIND 3-4 MPH 






15° 1 

^0° j 


— 

— 


—^ i i 

- 5°f 




— 



0 20 40 60 80 100 120 140 160 180 


YARDS DISTANCE TO CENTER OF DEPOSIT 

Figure 19. Effect of elevation on range of 0.75-in. 

nozzle using 8 per cent gel. 

the optimum elevation of a jet shooting into a 
wind of high velocity is considerably lowered. 

Temperature. The viscosity of thickened 
fuels, like that of Newtonian liquids, is de¬ 
pendent to some extent on the temperature. 
However, no genet'al relation has been found 
which expresses fuel consistency as a function 
of temperature. The temperature-consistency 
curves (Figure 20) exhibit low values at low 
temperatures and then pass through a maxi¬ 
mum in the vicinity of 50 F.-' It will also be 
noted that the percentage of decrease appears 
to be greater for the low concentrations. How¬ 
ever, the relatively flat consistency-range curves 
shown in Figure 16 indicate the small effect 
that temperature could have upon the range by 
changing the consistency. The temperature co¬ 
efficients for peptized fuels are even more diffi¬ 
cult to predict, but their magnitude is smalP® 
though somewhat greater than for unpeptized 
fuel. 

A more important effect of fuel temperature 
is its influence upon the ease of ignition. For 
unthickened fuels and thickened fuels up to 200 
Gardner consistency, ignition is complete over 
the entire range of temperature that might be 


encountered in operation. As the consistency 
increases, ignition at the lower temperatures 
becomes increasingly more difficult until finally 
no ignition occurs at all. In Figure 21 a fuel of 
200 Gardner consistency shows no variation in 
range with temperature, while a fuel of 400 
Gardner is independent of temperature only 
above 80 F. Below 80 F there is only partial 
ignition, and hence there is a proportional re¬ 
duction in range. For still greater consistencies 
no ignition occurs at all below certain tem¬ 
peratures. It is this sensitivity of thickened 
fuels to ignition at low temperature that has 
led to the continued use of secondary fuel. 

Wmd. Wind has two effects upon an ignited 
jet. First, the component of the force of the 



Figure 20. Influence of temperature upon the 
consistency of Napalm gels. 


wind along the jet tends either to decrease or 
increase the range, depending upon the wind 
direction with respect to the jet. Secondly, the 
factors which increase the range of an ignited 
jet over an unignited jet (see Section 7.6) are 
substantially reduced by the wind. Although the 
force along the jet can act either in a positive 
or negative direction with respect to the direc¬ 
tion of the jet, the factors that make greater 
range possible for an ignited jet are always 
adversely affected. 


pONFlDE ^tAfa—^ 






































































184 


STUDIES ON FLAME-THROWER DESIGN 


In Figure 22 range data at several wind in¬ 
tensities are shown as a function of wind direc¬ 
tion. If the effect of wind on range were only 
the effect of the force component, the per cent 



Figure 21. Effect of fuel temperature on jet igni¬ 
tion and range. (Gardner consistency: A, 200; 
B, 400; C, much higher.) 


increase for a tail wind would be approximately 
the same as the per cent decrease for an 
equivalent head wind, but from Figure 22 it 
is clear that this is far from the case. For a 10- 
mile head wind the per cent reduction of the 
range is about 40 per cent, but with a tail wind 
of the same intensity the per cent increase is 
less than 10 per cent. This effect of wind prob¬ 
ably accounts for more mistaken judgments of 
flame-thrower performance in field demonstra¬ 
tions than any other factor. 

Calculation of the expected effect of wind on 
flame-thrower range for a given nozzle eleva¬ 
tion involves a consideration of the two effects 
mentioned above. By a simple vector analysis, 
the normal and forward components of any 
wind on the jet may be determined. The range 
of an unignited jet relative to the wind may 
then be computed from the Rosin-Fehling cor¬ 
relation based on the Froude number {u-/gD) 
and the Reynolds number (tipD/n). From an 
estimation of the time of flight, the range rela¬ 
tive to the ground may be approximated. For 
unignited jets such an analysis yields results 


which agree within 10 per cent of experimental 
values. 

The problem of predicting the effect of wind 
on an ignited jet is considerably more complex. 
One method of approach is to consider the effect 
of wind on a factor x' which corrects for the 
range of ignited jets from unignited ones. The 
only analysis of this problem was based upon 
the Rosin-Fehling correlation of range versus 
Reynolds and Froude numbers, and therefore x' 
does not quite correspond with the final x that 
is given in the section on Range Correlation.-® 

A possible method of relating x',,. and x' to 
measurable quantities is to express the dimen¬ 
sionless group x\y — x'/l — t' as a function of 
the angle that the jet makes with the wind for 
various values of the Froude number. The 
smooth curves in Figure 23 are based on data 
from several sources.®’ x' was assumed to 
have a constant value of 0.3, and the choice of 
the Froude number using the normal component 
of the wind was based on the evidence that 
large jets were less affected by wind than 
smaller ones. 

This method of analysis is at best only 
approximate but represents the best correla¬ 
tion with the available data." The effect of gun 
elevation with wind upon range has already 
been discussed under gun elevation. 

Ignition and Secondary Fuel. The dependence 
of the range upon ignition makes it absolutely 
necessary that good ignition be assured. The 
numerous techniques of igniting the jet have 
been discussed under the individual flame 
throwers in Chapters 4 and 5. The major re¬ 
quirement is that the ignition system function 
under the most adverse conditions. Careful en¬ 
gineering design, with an appreciation for field 
conditions, has produced quite reliable ignition 
systems. 

It has been pointed out already that if ignition 
depended upon the flame produced by the com¬ 
bustion of a gasoline spray on a jet, the fuel 
consistency would have to be low and the fuel 
temperature high. For the purpose of rein¬ 
forcing ignition of the jet some flame throwers 
have secondary fuel which reduces the minimum 

More comprehensive data on wind effect, not avail¬ 
able at the time of the above correlation, appear in 
OSRD Report 5933, Figures 4-7. 


§ONFID^mMr] 















OPERATING VARIABLES 


185 


WIND 

0 M P H J34 YDS 


WIND 
5 M P H 

WIND \ 

10 M P H 



V=Z20 F P S 
RE^ 6 
(p » 15** 

Figure 22. Effect of wind on range of V^-in, flame-thrower nozzle. 


SoNFIDEgTIg^ 

























186 


STUDIES ON FLAME-THROWER DESIGN 


operating temperatures, maintains ignition in 
wind, and raises the maximum usable fuel con¬ 
sistency. Another method, besides the use of 
secondary fuel for maintaining ignition on the 
rod, is the provision of a hot flame confined 



Figure 23. Relation between t, p, and Uxc, where 
p is the angle that the jet makes to the wind. 


between the gun barrel and the outer shroud.-'* 
It is believed that this method would prove in¬ 
adequate under adverse conditions of wind and 
temperature. 

The data available on the application of sec¬ 
ondary fuel are meager, although several flame 
throwers have been designed with secondary 
fuel. Model Q was the first to incorporate the 
principle of secondary fuel, and in this early 
model the gasoline was added to the rod through 
a porous metal sleeve located just before the 
nozzle. The porous metal was later replaced 
by a perforated cylinder. For a V^-in. nozzle a 
rate of 1.0 per cent of the primary fuel was 
used at first, but was later increased to 3.5 per 
cent. This higher rate reduced the minimum 
operating temperature to 10 F for an 8 per cent 
gel. For an additional factor of safety the rate 
was further increased to 4 per cent. 

Somewhat more detailed experiments on the 
optimum operating conditions for secondary 
fuel were reported by the Standard Oil Co. 
(Indiana) group.The method that this group 
used to apply the secondary fuel to the jet has 
already been described in the section on nozzle 
design. A study of the rate of addition of sec¬ 
ondary fuel indicated that there is an optimum 


rate. At high rates, the rod burns with a bush 
flame, the appearance of which indicates that 
too much fuel has been added and the excess is 
being burned off. For a i/4-in. jet it has been 
found that 3 to 5 per cent by volume gives the 
best results. 

In the initial stages of the investigation it 
was thought that the viscosity of the secondary 
fuel would be a measure of the efficiency of the 
fuel. However, experiments failed to show any 
correlation between the viscosity and the igni¬ 
tion of the rod. The Indiana group finally 
arrived at a 50-50 blend of gasoline and No. 30 
SAE motor oil, which appeared to give the best 
performance for their particular gun. 

CDRRELATION OF RANGE DATA 

Uuignited Jets. The desirability of being able 
to predict the range of a flame thrower under a 
given set of conditions is obvious. Several in¬ 
vestigators have analyzed small experimental 
jets under controlled conditions,*’and the 
results of the work have been extended to ac¬ 
tual flame-thrower jets. 

An early correlation by the Eastman Kodak 
group showed the range of an unignited jet to 
be a function of the apparent viscosity of the 
fluid. In their analysis a large number of New¬ 
tonian liquids varying in viscosity from 0.006 
to 190 poises, pseudoplastic liquids with pro¬ 
nounced rigidity, a dilatant mixture, and a 
pseudoplastic material having a yield value 
were ejected from an Vr.-ii^- nozzle at varying 
momentums. The range-momentum plot of the 
data gave a variety of curves, but all curves lay 
in order of their viscosity, or apparent viscosity, 
measured on the MacMichael viscosimeter. This 
relationship suggested a possible correlation of 
apparent viscosity and range which is shown by 
plotting on semilog paper the range at an ini¬ 
tial kinetic energy equivalent to «o“ Pf, = 50,000 
against the apparent viscosity (poises) at this 
rate of shear, 30 reciprocal sec (Figure 24). 
For the fluids studied the correlation appeared 
to give good results, as was evidenced by the 
smooth curve that was obtained. 

A more general correlation for unignited 
Newtonian liquids, and valid for some non- 

































COHH EL AT ION OF R ANGE DATA 


187 



0.1 1.0 10 100 1000 10,000 
APPARENT VISCOSITY IN POISES AT A VELOCITY GRADIENT 30 SECONDS 


Figure 24. Range versus apparent viscosity for Vs-in. nozzle. 


Newtonian liquids, was found by Rosin and 
Fehling, This was based upon the range number 
•V, D.pa/pl, a modified Froude number iin-pA/gD. 
Pa: PL, and the Reynolds number DuqpJpj^. Fig¬ 
ure 25 shows the curves obtained from this 
correlation, which was difficult to apply to the 
ignited jet. 

In one series of experiments a du Pont group 
measured the momentum of a jet at a target 
located a known distance from the nozzle.-^ 
Figure 26, showing jet reaction (force of a jet 
on a target) plotted against the distance of the 
target from the nozzle, illustrates the type of 
curves obtained for all liquids that were studied. 
The horizontal portion of each curve corre¬ 
sponds to substantially frictionless projection 
of the jet, but as the jet begins to break up, 
the fractional decrease in momentum becomes 
linear in distance. An analysis of the forces 
acting on the jet to produce this effect follows. 

The drag force on the unit mass of the jet is 
expressed in terms of the drag coefficient by the 
equation: 


F= 


C dU~ p.i-l ' 

2g 


or in terms of deceleration 
g 


p._py' dll _pV'udu 
dt gdx' 


whence. 


, _2pLV'dii. 
PAA'ndx' 


(d) 

( 6 ) 


The jet reaction is given by the expression 



(7) 



Figure 25. Rosin-Fehling correlation for flame¬ 
thrower range. 

Then the change of jet reaction with distance 
from the nozzle is 

d. In P/{ _ C dPaA ' 

^d ^" F'p/, 


fCONFlDENTlAL 0 


( 8 ) 
















































































































































188 


STUDIES ON FLAME-THROWER DESIGN 



NOZZLE 

DISCHARGE 

NOZZLE 





DIAMETER 

COEFFICIENT 

PRESSURE 

SLOPE 




IN. 


LB/SQ IN. 




0 

0.038 

0.92 

250 

0.275 



A 

0.038 

0.91 

200 

0.247 



□ 

0.035 

0.92 

150 

0.18 0 



+ 

0.0 35 

0.90 

99-104 

0.139 



• 

0.035 


54-57 

0.075 



■ 

0.035 

0.92 

46-47 

0.069 

3% 

NAPALM 

X 

0.0 35 


25-28 

0.037 

6% 

NAPALM 



NOZZLE 

DIAMETER 

IN. 

0.035 
0.0 35 


DISCHARGE NOZZLE 
COEFFICIENT PRESSURE SLOPE 
LB/SO IN. 


0.75 

0.62 


149-154 

148-150 


0.272 

0.179 



NOZZLE 


I 2 3 

DISCHARGE 


5 6 7 

NOZZLE 


10 II 12 
VISCOSITY 


DIAMETER COEFFICIENT PRESSURE SLOPE TEMP CENTIPOISES 



3 4 5 6 7 8 ‘9 10 II 12 


3 4 


7 6 9 10 II 12 


NOZZLE DISCHARGE NOZZLE VISCOSITY 

DIAMETER COEFFICIENT PRESSURE SLOPE TEMP CENTIPOISES 
IN. LB/SQ IN. ®C 


0.038 

0.038 

0.038 


1.09 

0.89 

0.88 


250 

150 

100 


0.254 

0.207 

0.157 


29.0 


15.6 



01 23456789 10 II 12 

NOZZLE DISCHARGE NOZZLE VISCOSITY 

DIAMETER COEFFICIENT PRESSURE SLOPE TEMP CENTIPOISES 
IN. LB/SQ IN. *C 


0.038 

0.038 


0.89 

0.60 


245 

150 


0.298 

0.252 


26.0 


13.5 



01 23456789 10 II 12 

DISTANCE FROM NOZZLE TO TARGET IN FEET 


NOZZLE DISCHARGE NOZZLE 
DIAMETER COEFFICIENT PRESSURE SLOPE 
IN. LB/SO IN. 


0.038 
0.037 
0 035 


0.85 

0.80 

0.86 


210 

210 

150 


-0.189 

-0.153 

-0.105 



0 I 

NOZZLE 

DIAMETER 

IN. 

0.038 

0.038 

0.038 


2 3 4 

DISCHARGE 

COEFFICIENT 


0.86 

0.90 

0.90 


7 8 9 10 II 12 


NOZZLE 
PRESSURE 
LB/SQ IN. 

250 

200 

150 


SLOPE 

oTi^ 

0.310 

0.275 


VISCOSITY 
TEMP CENTIPOISES 
®C 


26.5 


5.5 



01 234 5 67 89 10 II 12 

DISTANCE FROM NOZZLE TO TARGET IN FEET 


Figure 26. Jet reaction data. 


r mNFIDENf lAlT) 




















































































































































































































































CORRELATION OF RANGE DATA 


189 


Denoting CdpaA’ jlV a, equation (8) be¬ 
comes a = d\n piildx’. It is apparent, then, that 
the slope of the curves in Figure 26 is a. By 
making the heuristic assumption of a constant a 
over the entire trajectory, thereby neglecting 
the initial portion of the curve, an analysis of 
the trajectory can be made. 

Although equations have been derived for the 
trajectory of a jet,"--^ they are too cumber¬ 
some for direct practical use. However, it is 
possible to express the relationship in the form 


y it/ 


= 0 . 


(9) 


In Figure 27, .rg/«o“ is plotted against aiio'^/g for 
various values of a|', and from these curves it can 
be seen that once the value of a is determined, the 
range can be estimated. From the definition of 
OL, aD = (Cdpa)/‘^pl (A'D/V'). If it is assumed that 


question is assumed a simple power product of 
these variables aD may be expressed as follows: 

•'>=‘■('77)' (”:“)■ O'- <'"■ 

The drag force from equation (4) becomes 

p,_ aUo-V pL ^ j'jj) 


The shearing stress / is given by 

Substitution from (11) into (12) gives 

^_/aUo‘pL\ /V'\_/'ali(fPL\ D 

^ \ g ) \a) \ g ) H 03 ) 

where (3 equals four for a cylindrical jet of di¬ 
ameter equal to nozzle diameter and six for a 



Cijand the particle shape, as measured by A 79/F', 
are determined by (1) the Reynolds number 
Iuqpa/pa which affects the shearing force of the 
atmosphere against the jet, (2) the Reynolds 
number Dugipt/p-L which depends upon the inter¬ 
nal shearing forces in the liquid jet, (3) the 
Froude number uHgD, and if the function in 


spherical particle of diameter equal to nozzle 
diameter. As an approximation, a value of five 
is assumed. 

Using experimental data, with equation (10) 
as a guide to a correlation, the following rela¬ 
tions were determined for fuels having a specific 
weight of 47 lb per cu ft. 


HBBTdential? 







































190 


STUDIES ON FLAME-THROWER DESIGN 


For nozzles with a short cylindrical section 
= 1.07X10- 

and for conical nozzles 



(14) 

'/)0.2q^^0.3<A 

(15) 


equation (13), the shearing stress becomes for 
cylindrical nozzles 

/nO.18,, 0.36\ ,, 2 

/=10.1X10-* r X )-■ ( 16 ) 

For conical nozzles 




,/= 11.4X10--' 




Ml" 


(17) 



To be able to calculate the range for non- 
Newtonian liquids from these equations, it is 
necessary to find the relation between the shear¬ 
ing stress / and the viscosity n;;. In Figure 28 
the smoothed curves were plotted from experi¬ 
mental data for a range of Gardner consist¬ 
encies. Using Figure 28 together with equation 
(16) or (17) it is possible to determine the 


range of an unignited jet when the nozzle veloc¬ 
ity, nozzle diameter, fuel consistency, and nozzle 
elevation are known. By trial-and-error, that 
value of / is found which predicts the same 
valus for j,i/, from Figure 28 and by use of 
equation (16) or (17). Equation (14) or (15) 
is then used to determine a, after which Figure 
27 may be used to determine range. 

The above procedure leads to a prediction of 
average range. Experimental data indicate that 
the ratio of a for the maximum range to a for 
the center of deposit varies from 0.55 to 0.85. 
Using an average value of 0.7, the difference 
between the farthest particles and the center 
of deposit can be estimated. 

Ignited Jets. Referring to equation (9), it can 
be seen that the only change in an ignited jet 
over an unignited one is a change in the value 
of a. An analysis of an ignited jet shows that 
the following factors affect the value a and, 
hence, the magnitude of the range. 

1. The temperature of the air, or rather the 
envelope of the jet, is increased, with a cor¬ 
responding decrease in p .4 resulting in a de¬ 
creased a. 

2. The reaction due to the generation of com¬ 
bustion products at the trailing ends of the jet 
particles reduces the net drag forces and thus 
decreases a. 

3. The combustion of fuel tends to reduce the 
weight-to-area ratio of the particles and, there¬ 
fore, increases a. 

An additional factor, which has the same 
effect on range as a reduced a, is the lessening 
of the net downward force acting on the jet 
on account of the up-draft of the combustion 
gases. Since a reduced a causes an increased 
range, all but one of the above effects tend to 
increase the range of an ignited jet. 

In order to predict the range of an ignited 
jet a factor t has been introduced, which is 
the ratio of o,. ignited to a unignited. From ex¬ 
perimental data it appears that t for complete 
ignition is approximately a function of aiid-fg, 
as is shown in Figure 29. x is in effect the ratio 
of the absolute temperatures of the gas mantles 
around cold and ignited jets, respectively. 

Partially Ignited Jets. In the zone of partially 
ignited jets prediction of the range is much less 
reliable. The intensity of ignition depends at 


rOONFIDENTIAin 
























































































































CORRELATION OF RANGE DATA 


191 



<3 

Figure 29. Relation of t to otu^-/g in region of 
complete ignition. 


least upon the jet velocity, fuel viscosity, and 
fuel temperature. In Figure 30 the Reynolds 
number at fair ignition is plotted against the 
Froude number for different temperatures. For 
a constant Reynolds number there exists a 



Figure 30. Relation among Reynolds number, 
Froude number, and fuel temperature, defining 
regions of good and poor ignition. 

velocity above which a jet cannot hold a flame; 
with higher Reynolds numbers, disturbances 
become greater and consequently the flame holds 
to the jet more easily. 


Nomenclature 


Symbol Quantity Units Dimensions 


A 

Surface area of unit mass of jet 

ftVlb 

lyM 

A' 

Total frontal area of particles 




comprising unit mass of jet 

ftVlb 

L^M 

B 

Nozzle diameter/piezometer ring 




diameter 



C 

Nozzle discharge coefficient 



Cd 

Coefficient of drag based on fron¬ 




tal area of particles 



D 

Inside diameter of nozzle or pipe 

ft 

L 

F 

Drag force on jet per lb fluid 

Ib/lb 

W/M 

G 

Consistency of fuel 

g 

.Arbitrary 

K 

Numerical constant 



L 

Length of pipe 

ft 

L 

P 

Pressure 

Ib/fU 

W/l? 

Pr 

Jet reaction 

lb 

IV 

Q 

Rate of flow 

fU/sec 

lyr 

R 

Shear rate 

sec~i 

\/T 

S 

Specific gravity 



V’ 

\’olume of particles/lb 

ftVIb 

U/M 

d 

Denotes differential 



f 

Shear stress 

Ib/fU 

IF/L2 

g 

.Acceleration of gravity 

ft/sec^ 

L/T'i 

k 

Numerical constant 

t/sec^ 

L/T’^ 

1 

Average length of particle 

ft 

L 

m 

Numerical constant 



rn’ 

.Average weight of particle of jet 

lb 

11' 

n 

Numerical constant 



P 

Numerical constant 



u 

Jet velocity 

ft/sec 

L/T 

u 

Mass velocity of jet 

Ib/sec 

M/T 


Wlocity of jet from a nozzle 

ft/sec 

L/T 

u' 

\'elocity of fluid in conduit 

ft/sec 

L/T 

X 

Horizontal distance from nozzle 

ft 

L 

x' 

Distance along trajectory 




from nozzle 

ft 

L 

y 

X'ertical distance from nozzle 

ft 

L 

a 

CdpaA'/2V'pl, unignited 




conditions 

ft-i 

\/L 

ai 

CdpaA'/2\''pl, ignited conditions 

ft-i 

\/L 

/3 

Numerical parameter 



A 

Finite increment 




Effective viscosity 

lb mass 

M/LT 



sec“^ ft“i 


MO 

\’iscosity at standard shear rate 

lb mass 

M/LT 


sec ‘ ft ^ 

lb mass M/LT 
sec“'f t“^ 

lb mass M/LT 
sec“‘ ft“i 
Ib/fU W/L^ 

lb/ft3 W/L^ 


y.L Viscosity of fuel 

ixA \’iscosity of atmosphere 

surrounding jet 
PL Specific weight of fuel 

PA Specific weight of atmosphere 

surrounding jet 

r Ratio a ignited to unignited 

t' Density number modifier for 

no wind 

t'u- Density number modifier 

4> Denotes “function of” 

y/' Slope of trajectory 

i/'o .Angle of nozzle with horizontal 


[cONFI DENTmtr^ 
















































































Chapter 8 

FUELS FOR INCENDIARIES AND FLAME THROWERS 


INTRODUCTION 

F uels used in incendiary bombs and flame 
throwers played an important part in World 
War II. In fact, the contribution of these fuels 
resulted in using fire as a weapon to a far 
greater extent in this war than in any previous 
war in history. Of the fuels used, by far the 
most important was gasoline gel thickened with 
Napalm. This fuel, in varying consistencies, was 
used in the following important weapons in 
World War II: 

AN-M47, 100-lb incendiary bomb, AN-M69, 
6-lb incendiary bomb, portable flame throwers, 
flame throwers mounted in tanks, and jettison- 
able gasoline tanks, dropped from fighter air¬ 
planes. 

This type of fuel was developed by NDRC. 
During 1942 and 1943 some AN-M47 and 
AN-M69 bombs were filled with gasoline gel 
thickened with isobutyl methacrylate poly¬ 
mer (IM). This material was developed by the 
duPont Co. under the joint sponsorship of 
NDRC and the Chemical Warfare Service. 

The only other fuels actually used in the war 
were some fortified or pyrotechnic fuels (PT) 
consisting of mixtures of hydrocarbons, metals, 
and oxidizing agents which were used in the 
M74 and AN-M76 incendiary bombs. These 
fuels were developed by the Chemical Warfare 
Service. 

The other types of fuels described in this 
chapter were experimental attempting to cor¬ 
rect one drawback or another of Napalm-thick¬ 
ened gasoline fuels, or which were developed 
for some special use. In Section 8.3 are de¬ 
scribed liquid thickening agents, which arose 
from the desirability of mixing fuels in the field 
or on an aircraft carrier by simply mixing two 
liquids rather than a solid and a liquid. Section 
8.4 describes methacrylate thickening agents, 
which were a valuable substitute until Napalm 
was fully developed. Sections 8.5 and 8.6 de¬ 
scribe two possible substitutes for Napalm or 
methacrylate thickening agents in case both of 
these became in short supply. Section 8.7 de¬ 


scribes fortified fuels which were more fiercely 
burning and less easily extinguished by water 
than ordinary gasoline gels. Section 8.8 de¬ 
scribes self-igniting fuels which have an obvious 
interest both in flame throwers and in in¬ 
cendiary bombs. Sections 8.8, 8.9, and 8.10 de¬ 
scribe fundamental studies which were under¬ 
taken better to understand the nature and 
modus operandi of thickened fuels. 


82 NAPALMi-4 

Introduction 

The gasoline thickening agent called Napalm 
is an aluminum soap of naphthenic, oleic, and 
coconut oil acids, of which the most common 
formula uses 50 per cent coconut oil acids, 25 per 
cent naphthenic acid, 25 per cent oleic acid. 
The development of a new thickening agent for 
gasoline made from readily available materials 
was dictated by the unavailability of rubber for 
this purpose after December 1941. The develop¬ 
ment of Napalm was initiated by Harvard Uni¬ 
versity in December 1941 under Contract 
OEMsr-179. In March 1942 Nuodex Products 
Co. came into the picture and made major con¬ 
tributions to the early development of Napalm, 
although their work was not formalized by 
Contract OEMsr-677 until August 1942. Other 
contributors to the development and improve¬ 
ment of Napalm were Arthur D. Little, Inc., 
working under Contract OEMsr-242, Standard 
Oil Development Co. under Contracts OEMsr- 
183, 354 and 390, Eastman Kodak Co. under 
Contract OEMsr-538, Harshaw Chemical Co. 
under Contract OEMsr-847, and Ferro-Drier 
and Chemical Co. under Contract OEMsr-882. 

By February 1942 three types of soap 
thickening agents which showed considerable 
promise had been developed by Harvard Uni¬ 
versity.^ These were designated as (1) Palmene, 
aluminum palmitate and neo-fat 3R (40 per 
cent oleic, 60 per cent linoleic acid), (2) oleo- 
palm, aluminum oleate and aluminum palmi- 


NAPALM 


193 


tate, and (3) Napalm, aluminum naphthenate 
and aluminum palmitate. 

The first Napalm was made by putting 
aluminum naphthenate through a meat grinder 
with wood flour and milling aluminum palmitate 
into the mixture. A dry powder resulted which 
could be dispersed in gasoline at ordinary tem¬ 
peratures. A subsequent mixture of one part 
aluminum palmitate, one part aluminum naph¬ 
thenate, and two parts of kerosene agitated 
in a dough mixer at 100 F was found to be 
greatly superior in toughness and stability. 
This tough, gummy mixture was incorporated 
into gasoline by passing it through a meat 
grinder and agitating the disintegrated ma¬ 
terial in the gasoline with a stirrer, or by circu¬ 
lation through a gear pump. Later, half the 
naphthenic acid was replaced with oleic because 
of the reported shortage of the former. Nuodex 
Products Co. found that this modified Napalm 
could be produced by means of a coprecipitation 
process as a dry granular solid readily dis¬ 
persible in gasoline at ordinary temperature. 
Because of the ease of manufacture and of 
mixing with gasoline, this material was stand¬ 
ardized, and manufacture was begun in Decem¬ 
ber 1942. A total of about 80,000,000 lb was 
produced before the end of World War 11. 

Although practically all Napalm has been 
manufactured according to the standard for¬ 
mula (25 per cent oleic, 25 per cent naphthenic, 
50 per cent coconut oil acids), additional re¬ 
search, both in this country and in England, 
has shown that the aluminum soaps of practi¬ 
cally all combinations of these acids, including 
100 per cent oleic or 100 per cent naphthenic, 
are moderately satisfactory gasoline thickeners, 
although varying considerably in specific physi¬ 
cal properties. However, if more than about 80 
per cent coconut acids are used, the resulting 
soap cannot be dispersed in gasoline at room 
temperature. The British used aluminum stea¬ 
rate-thickened fuels exclusively. These fuels 
were factory-mixed at 120 to 130 F. 


Manufacture 

Ge^ieral. At various times during the period 
1943-1945 the following nine companies were 


engaged in large-scale production of Napalm: 
Nuodex Products Co., Imperial Paper and Color 
Corp., Ferro Enamel Corp., McGean Chemical 
Company, Pfister Chemical Co., J. S. and W. R. 
Eakins Co., California Ink Co., Oronite Chemi¬ 
cal Co., and Harmon Color Works. In addition, 
a few batches were manufactured by Colgate- 
Palmolive-Peet Corp. All manufacturers used 
some variation of a process in which the water- 
insoluble, basic aluminum soaps of the mixed 
acids were coprecipitated from aqueous solu¬ 
tion. Variations in precipitation and drying 
methods were largely attributable to differences 
in the equipment which was available to the 
individual manufacturers. 

The most commonly used precipitation proc¬ 
ess is a batch process in which the total amount 
of caustic required, about 60 per cent in excess 
of the amount necessary to neutralize the acids, 
is added to the mixed acids, the alum then 
being added gradually until the precipitation is 
complete. In one variation of this method only 
enough caustic is added to the mixed acids to 
produce the stoichiometric soap solution, the 
balance being added with the alum solution. In 
this second method the precipitation is begun 
at a lower pH and the separation of aluminum 
soap is more gradual than in the standard batch 
method. In addition to the batch methods, a 
continuous two-stream precipitation technique 
was developed by one manufacturer, Eakins. 
This involves the addition of controlled streams 
of the alum and sodium soap solutions to a 
vessel supplied with vigorous agitation. The 
alum added in the first stage is insufficient to 
cause coagulation of the soap, and the resultant 
milky solution overflows into a second vessel 
along with another stream of alum to form an 
excess of this reagent. The suspended precipi¬ 
tate then flows to a washing and draining device. 
The first-mentioned batch method has been most 
generally used and was early recommended as 
a standard process.The two-stream method 
requires less space for the equipment used, and 
in addition, yields a particularly fast setting 
variety of Napalm which is desirable in certain 
applications. 

Raw Materials .Variations in acid quality 
may be responsible for considerable differences 
in the character of the soap produced. Regular 


ifcnNFT DRNTTATr]^ 




194 


FUELS FOR INCENDIARIES AND FLAME THROWERS 


laboratory testing of new shipments of acid is 
a necessity for satisfactory Napalm production. 
The following specifications have been found 
suitable. 



Coconut 

Naphthenic 

Oleic 


oil acids 

acid 

acid 

Acid 

number 

260-270 

230-245 

190-200 

Iodine 

number 

Below 15 

Below 10 

85-90 

Iron 

Below 0.01% 

Below 0.01% 

Below 0.01% 

Unsaponi- 

fiable 

2% maximum 

Below 8% 

Below 2% 

Titer, F. 

75-77 


46-54 


At first it was considered necessary to use only 
rectified naphthenic acids, but as supply became 
critical, crude naphthenic was used with en¬ 
tirely satisfactory results. The use of high acid- 
value coconut oil acids results in Napalms of 
exceptionally high thickening power; hence 
this variable should be carefully controlled. 

Some difficulty was encountered at first with 
war-grade alums made from clay; this was on 
account of their high iron content. If possible, 
the iron content should be below 0.03 per cent 
and manganese below 0.01 per cent. These ma¬ 
terials are deleterious because of their action 
as oxidation catalysts; hence somewhat larger 
percentages can be tolerated if an oxidation in¬ 
hibitor such as alpha-naphthol is incorporated 
in the Napalm.It is recommended, however, 
that metallic impurities be kept at a minimum 
even if an inhibitor is used. 

Dewatering and Drying. The type of dewater¬ 
ing used prior to drying has little effect on the 
product. However, there is some evidence that 
if the wet pump is allowed to stand overnight 
or longer before drying, the thickening power 
of the Napalm is increased. Tray and continu¬ 
ous belt drying have been successfully used, 
the first being the most common. In tray drying, 
an air temperature of 160 F is optimum and a 
drying time of 15 to 20 hr is common for cake 
depths of approximately 2 in. In general, it is 
advantageous to use as high a drying tempera¬ 
ture as possible without causing undue oxida¬ 
tion or fusion. With belt driers and thin layers 
of material the drying temperature may be as 
high as 200 F and the drying time reduced to 
about 1 hr. At the end of World War II some 


contractors were beginning to install infrared 
drying equipment. 

Packaging. Napalm is packed in hermetically 
sealed containers. Package sizes for regular 
Napalm are 514 lb, 15% lb, and 100 lb; the 
first two were primarily for overseas shipment 
for field mixing of flame throwers and blaze 
bombs, and the last for shipment to arsenals 
and factories filling incendiary bombs. Ground 
Napalm for the Navy is packed in 60-lb con¬ 
tainers. Because of the moisture susceptibility 
of Napalm it is necessary that care be exer¬ 
cised in handling the Napalm between drying 
and packaging. Containers used for overseas 
shipment have been quite successful in prevent¬ 
ing contamination of the soap by moisture, as 
evidenced by testing of numerous samples re¬ 
turned from the various war theaters. 

Syecifications.^^ The most important Napalm 
specification is the one regarding thickening 
power, which is evaluated by the Gardner 
mobilometer. Gardner consistency is the weight 
in grams required to force the plunger through 
the material in the tube at a rate of 0,1 cm per 
sec. Originally, consistency was specified only 
for 8 per cent gasoline gels, the allowable range 
being 500 to 800 g after storage for one day 
at 77 F and at 150 F. Later special consistency 
tests were instituted for 6.2 per cent and 11.5 
per cent gels. The test gasoline used after about 
February 1944 was a high-boiling fraction 
(naphtha) supplied by the Continental Oil Co.. 
Baltimore, Maryland. This gave, in general, 
higher consistencies than the Standard Oil De¬ 
velopment Co. test gasoline used previously; 
the change was made because the naphtha, 
being low in unsaturates, was less likely to 
oxidize on long storage, and having a high 
boiling point lost less weight on handling and 
testing of the Napalm gels made from it. 

Additional specifications include moisture, 0.4 
to 0.8 per cent by CWS benzene distillation 
method, oxidation-inhibitor content, and gen¬ 
eral gel characteristics, stringiness, healing, 
etc. Gelation rate in gasoline was originally 
specified, but this specification was not in force 
during most of the period of production. 

Variability. Although comparatively little dif¬ 
ficulty was encountered by most manufacturers 
in producing Napalm which would pass speci- 


Icon fiIBBBBi^ 







NAPAL>[ 


195 


fications, the resulting products were quite dif¬ 
ferent in some respects. In general, however, 
each manufacturer’s product was quite uniform 
from batch to batch. The most important differ¬ 
ences were in setting rate, variation of con¬ 
sistency with concentration, and susceptibility 
to water and other additives. In general, Eakins 
Co., Pfister Chemical Co., and California Ink 


Co. produced fast setting Napalms, Nuodex 
Products Co. slow setting, and the Napalms pro¬ 
duced by others were intermediate. Setting 
times (6.5 per cent gels in test naphtha, 77 F) 
of ten samples from each manufacturer, pro¬ 
duced in the period June 1944 to January 1945, 
were determined by the Chemical Warfare Serv¬ 
ice Technical Command^^ by using the disap- 


Table 1. Consistency, stability, and moisture susceptibility of representative Napalms (1943). 



Condition 

Moisture 


Gardner consistency, grams 



% of relative 

CWS benzene 


4% gel 

8% gel 


Manufacturer 

humidity 

distillation 

1 day 

32 days 

1 day 

32 days 

McGean 

As received 

0.75 

195 

130 

770 

730 

462 

90 F-20 

0.85 

245 

90 

720 

660 


90 F-50 

1.45 

85 

46 

550 

440 


90 F-70 

2.2 

22 

8 

280 

220 

Ferro 

As received 

0.65 

258 

140 

770 

760 

1<S4 

90 F-20 

0.55 

255 

130 

770 

660 


90 F-50 

1.0 

170 

55 

670 

515 


90 F-70 

1.45 

72 

27 

445 

295 

Pfister 

As received 

0.7 

145 

88 

645 

625 

N3-2432-94 

90 F-20 

0.7 

145 

84 

675 

640 


90 F-50 

1.05 

90 

54 

575 

490 


90 F-70 

1.30 

57 

33 

490 

390 

Harmon 

As received 

0.7 

160 

80 

660 

600 

R 11285 

90 F-20 

0.75 

170 

80 

690 

610 


90 F-50 

1.0 

84 

42 

610 

410 


90 F-70 

1.2 

32 

21 

310 

215 

Oronite 

As received 

0.5 

250 

100 

960 

805 

J-33-C 

90 F-20 

0.45 

290 

115 

990 

840 

90 F-50 

0.7 

175 

54 

900 

680 


90 F-70 

0.95 

133 

27 

760 

460 

California Ink 

As received 

0.7 

160 

72 

620 

520 

98 

90 F-20 

0.85 

138 

74 

560 

480 


90 F-50 

1.1 

66 

34 

390 

320 


90 F-70 

1.55 

24 

17 

235 

225 

I mperial 

As received 

0.7 

110 

60 

640 

575 

NR-232 

90 F-20 

0.7 

74 

64 

830 

590 


90 F-50 

0.95 

60 

37 

510 

410 


90 F-70 

1.45 

51 

24 

330 

305 

N uodex 

As received 

0.7 

200 

125 

760 

690 

19889 

90 F-20 

0.95 

150 

120 

670 

650 


90 F-50 

1.2 

104 

69 

550 

500 


90 F-70 

1.7 

50 

43 

370 

360 

Colgate-Pal mol ive-Peet 
N3-2854-56 

As received 

90 F-20 

0.4 

0.5 

190 

150 

90 

72 

790 

710 

630 

570 


90 F-50 

0.75 

91 

51 

610 

435 


90 F-70 

0.95 

62 

36 

470 

325 

Eakins 

As received 

0.65 

90 

50 

570 

430 

N3-2981-431 

90 F-20 

0.45 

102 

66 

590 

515 


90 F-50 

0.7 

82 

51 

550 

380 


90 F-70 

1.05 

62 

42 

355 

310 


llffWWUENllALl 















196 


FUELS FOR INCENDIARIES AND FLAME THROWERS 


pearing vortex method. The average values for 
the different manufacturers are: Eakins 1.4 
min, Pfister 1.5 min, California Ink Co. 2.2 min, 
Imperial 4.9 min, Ferro 5.2 min, McGean 5.8 
min, Oronite 6.7 min. The fast setting of the 
Eakins soap appeared to be a result of the two- 
stream precipitation process. Ferro Enamel 
Corp. later changed to the two-stream method 
in order to produce fast setting Napalm for the 
Navy. Nuodex Products Co., which was no 
longer producing Napalm when the tests men¬ 
tioned above were carried out, obtained slow 
setting by wet densification and controlled com¬ 
minution. It is known that the setting rate can 
be controlled to some extent by means of the 
excess caustic ratio during precipitation. 

Table 1 gives data on variation in consist¬ 
ency, stability, and susceptibility to water for 
ten representative Napalms manufactured in 
1943.“^ Table 2 gives fragmentary data on 
samples received from six manufacturers early 
in 1945. 

The differences in concentration-consistency 
relationships were quite pronounced for Nuodex 
and Imperial Napalms. This was especially im¬ 
portant because for a time in 1943-1944 these 
two varieties were packaged for field mixing of 
flame-thrower fuels (5i/4-lb packages). Al¬ 
though both passed specifications and had simi¬ 
lar consistencies at 8 per cent, they were quite 
different at 4.2 per cent, the concentration com¬ 
monly used in the portable flame thrower. Com¬ 
parison of ten Imperial and ten Nuodex soaps 
showed a consistency range for 4.2 per cent gel 
of 52 to 96 for the former and 117 to 250 for the 
latter.-* Differences in setting rate were just as 
pronounced, the average for Nuodex samples 
being 25 min, for Imperial 13 min (4.2 per cent 
gels in motor gasoline). Because of probable 
confusion to men in the field, who might obtain 
either of these varieties from time to time, the 
Imperial product was in late 1944 standardized 
as the Napalm for flame throwers. Thereafter 
it was the only variety packaged in the 5i/4-lb 
container. 

As a result of the above mentioned variability 
in the soaps from different manufacturers. 
Napalm was placed on cooperative procurement 
in August 1944. During this period no specifica¬ 
tions were in force, and attempts were made by 


Table 2. Consistency and stability of representative 
Napalm gels (1945). 


Manu¬ 

facturer 

% 

Xylenol, % 

Gardner 

consistency grams 

1 day 2 weeks 

Imperial 

3 


16 


NR-17 64 

4 


48 



5 


135 

127 


6 


250 

210 


7 


390 

350 


8 


505 

540 


6 

1.25 

34 



9 

1.5 

173 

185 

McGean 

2 


15 


4778 

3 


40 



4 


151 

<84 


5 


270 

167 


6 


410 

260 


7 


500 

425 


8 


680 

555 


6 

1.25 

24 



9 

1.5 

240 

250 

Eakins 

2 


7 


480 

3 


64 



4 


171 

129 


5 


295 

260 


6 


410 

385 


7 


575 

565 


8 


740 



6 

1.25 

80 



9 

1.5 

470 

405 

Pfister 

2 


26 


N5-157-702 

3 


78 



4 


164 

124 


5 


245 

215 


6 


375 

385 


7 


490 

560 


8 


660 



6 

1.25 

97 



9 

1.5 

565 

465 

Ferro 

3 


32 



4 


89 



5 


200 

9 


6 


305 

210 


7 


485 

370 


3 


670 

540 


6 

1.25 

41 



9 

1.5 

295 

305 

Harmon 

2 


10 


N5-139-78 

3 


42 



4 


138 



5 


260 

230 


6 


380 

370 


7 


515 

560 


8 


750 

750 


6 

1.25 

90 



9 

1.5 

460 

600 
























NAPALM 


197 


Chemical Warfare Service in cooperation with 
the manufacturers to modify their various pro¬ 
cedures so as to produce more nearly identical 
soaps. These investigations resulted in special 
specification tests concerning inhibitor content 
of the finished soap, and consistency of 6.2 per 
cent and 11.5 per cent gels were instituted. 
The inhibitor-content specification was a result 
of tests indicating that susceptibility to pep¬ 
tizers was a function of the alpha- or beta- 
naphthol concentration in the finished soap. An¬ 
other specification change was reduction of the 
consistency range for the 150 degree test (8 per 
cent gels) to 550 to 750 g Gardner. The effect 
of these changes on Napalm uniformity has not 
been fully evaluated because World War II 
ended soon after Napalm went off cooperative 
procurement. Consistencies of 6.2 per cent gels 
of some of the last batches which were manu¬ 
factured are: Eakins 120, 140, 123; Imperial 
157, 190, 175, 148, 133; Ferro Enamel 172, 138; 
California Ink 107, 210; McGean 160, 235, 192, 
260; Oronite 157, 156; and Pfister 250, 260. 

The success of most of the manufacturers in 
producing a uniform type of Napalm over long 
periods indicates that the best means of improv¬ 
ing uniformity is production of all the material 
in a single plant under identical conditions. 


8.2.3 Thickened Fuels from Napalm 

General. Thickened fuels may be prepared 
with Napalm by adding the soap to the gasoline 
and stirring with a paddle, or mechanical 
stirrer, until the Napalm particles swell to the 
point that settling does not occur. This point 
has been termed the stir time, or set time, of 
the fuel. With 6 per cent Napalm at a tem¬ 
perature of 70 to 80 F the required time of 
stirring may vary from 0.5 to 10 min with 
different Napalms. At 4.2 per cent the stir time 
is somewhat longer, the average for Imperial 
Napalms being 13 min, as noted above. At tem¬ 
peratures below 60 F the stir time becomes very 
much longer, and it is almost impossible to mix 
fuels below 50 F without incorporating a low- 
temperature peptizer. At temperatures above 
90 F the stir time is quite short, particularly at 
the high concentrations used in incendiary 


bombs. In fact, under these conditions it may 
be impossible to obtain a homogeneous fuel be¬ 
cause of the mixture “setting up” before all the 
Napalm can be incorporated. For this reason 
incendiary bomb filling plants require refriger¬ 
ation facilities for cooling the gasoline in the 
summer months. 

In all applications in which thickened hydro¬ 
carbon fuels are used, such as flame throwers, 
blaze bombs, and incendiaries, ordinary Na¬ 
palm-gasoline mixtures, prepared as described 
above, give satisfactory performance. However, 
numerous experiments have shown that Gard¬ 
ner consistency, irrespective of Napalm con¬ 
centration, is a reliable guide to the per¬ 
formance of these weapons with Napalm fuels. 
Thus additives which impart properties desir¬ 
able in the preparation, handling, or storage 
of Napalm fuels may be incorporated even 
though they raise or lower the consistency, as 
long as the Napalm concentration is adjusted 
to give the desired consistency. Most additives 
which have been used lower the fuel consist¬ 
ency. These additives, commonly designated as 
peptizers, will be discussed in the section on 
“Peptized Fuels,” p. 199. 

Thickened Fuels for Portable Flame Throiv- 
ers. The recommended mix for the portable 
flame thrower is 4.2 per cent Napalm in ordi¬ 
nary motor gasoline (one 5i/4-lb can in 20 gal). 
With most Imperial Napalms this produces a 
consistency of 75 to 100 g, and tests by various 
groups engaged in research on flame-thrower 
fuels indicate that this is about the consistency 
which gives optimum long-range performance 
in the portable flame thrower. Variations re¬ 
sulting directly from gasoline quality,the use 
of a different Napalm, or accidental introduc¬ 
tion of water or other peptizers during mixing 
might easily result in 4.2 per cent fuels of con¬ 
sistencies anywhere in the range 25 to 250 g 
Gardner. Although, generally speaking, no in¬ 
struments for measuring consistencies were 
available in the field, men in charge of mixing 
became capable of estimating consistency of 
fuels from their handling characteristics, poura- 
bility, etc., and reports from the field indicate 
that numerous alterations in the basic formula 
were made in order to obtain the desired mix¬ 
ing and firing characteristics. In addition to 





198 


FUELS FOR INCENDIARIES AND FLAME THRO\^ ERS 


the change of Napalm concentration, these vari¬ 
ations included incorporation of water, xylenol, 
silica gel, diesel oil, and motor oil. Some of these 
formulations will be discussed in separate sec¬ 
tions below. 

Thickened Fuels for Mechanized Flame 
Throivers. Mechanized flame throwers are those 
which are mounted on a vehicle, as opposed to 
portables which are carried on a man’s back. 
Mechanized models which have a small, 
nozzle use about the same fuel as portables, but 
models with larger nozzles, V 2 to 1 in., can 
profitably employ a fuel of somewhat higher 
consistency. 

Mechanized flame throwers with large nozzles 
have been used very little by the U.S. Forces. 
The Navy Mark I flame thrower (E7 gun), de¬ 
veloped by Standard Oil Development Co., saw 
action in the Peleliu invasion. As a result of 
tests which had been carried out at SOD the 
fuel recommended for this gun was 7 per cent 
Napalm, approximately 400 to 500 Gardner. It 
was found that fuels of this concentration 
mixed on Peleliu gave a somewhat more bushy 
flame than desired and the concentration was 
increased. However, Lt. Williams of the Navy, 
who was in charge of the mixing operations, 
stated that the fuels mixed on Peleliu appeared 
to be considerably below normal in consistency. 
According to the statements of Lt. Williams, a 
rod-like flame was desired for ease of aiming, 
with a burning time sufficient to set off the 
ammunition stored inside pillboxes. 

A critical study of the effect of fuel consist¬ 
ency on mechanized flame-thrower performance 
has been carried out by CWS-NDRC Flame 
Thrower Evaluation Group and the Flame At¬ 
tack Section of the Medical Division, CWS, at 
Edgewood Arsenal. The bulk of the tests dealt 
with the lethal effects of thickened fuel shot 
into a pillbox, live goats being used as subjects. 
The tests showed that the fuel consistency for 
the best compromise among lethality, effective 
range, ease of handling, and aimability is 200 
to 250 g Gardner. 

The tests further show that for fuels varying 
from unthickened to 200 g consistency, roughly 
1 gal per 1,000 cu ft of volume is required to 
kill the occupants. The required quantity of fuel 
increases with increasing fuel thickness up to 


approximately 2 gal per 1,000 cu ft for fuels 
of 700 g consistency. Maximum effective range 
was construed to be the maximum range at 
which all goats in the bunker were killed. No 
increase in maximum effective range, above 80 
yd, was observed on increasing the consistency 
above 200 g. It is possible to refuel flame 
throwers from light drums with 20 psi pressure 
with fuels of 200 g consistency, but it is im¬ 
possible for fuels higher than 400 g consistency. 
Interference to visibility due to bushy flame is 
slight for fuels of 200 g consistency, though 
somewhat greater than for fuels of 400 to 700 g 
consistency. 

Ranges in excess of 200 yd (center of de¬ 
posit) can be attained with large nozzles if fuel 
consistency is increased to 1,000 g Gardner. 

A gun elevation of 15 degrees or more is re¬ 
quired, and the fuel falls at a very steep angle 
at extreme range. Hence, aimability is greatly 
reduced, and the usefulness of such a weapon 
is limited to area firing, as in landing operations 
and river crossings. 

Thickened Fuels for Blaze Bombs. A con¬ 
siderable amount of Napalm was used by both 
the Army and the Navy for thickening gasoline 
used in filling the droppable fuel tanks known 
as blaze bombs. The optimum consistency for 
this application was 200 to 400 g Gardner. 
Lower consistencies resulted in too much flash 
burn, higher consistencies in incomplete igni¬ 
tion of the fuel. Some of the fuel used by the 
Army in the European theater was mixed by 
National Oil Refineries Ltd. in England, the 
remainder, by chemical companies behind the 
lines. Eakins, Ferro, Imperial, and McGean 
Napalms were used at Llandarcy. Concentra¬ 
tions of 5.7 to 6.7 per cent were required to ob¬ 
tain the desired consistency. Parts of each batch 
were retained, and stability was generally satis¬ 
factory over a five-month surveillance period. 

For Navy use, a thickener was required which 
could be mixed continuously with gasoline on 
the deck of an aircraft carrier, since the tanks 
had to be filled on the planes just prior to the 
take-off. An injector-type mixer, similar to that 
used in producing foams for fire fighting, was 
developed by National Foam Systems, Inc., in 
conjunction with the Navy. The need for an 
especially rapid-setting Napalm for use in this 



napal:\[ 


199 


equipment led to the development of ground 
Napalm containing finely divided magnesium 
carbonate which served as a grinding aid and 
anti-agglomerant. Practically all this material 
was produced by Ferro Enamel Co, which con¬ 
verted its plant to use the two-stream pre¬ 
cipitation process in order to obtain as fast 
setting a soap as possible. Laboratory tests 
have shown that the magnesium carbonate is 
not entirely satisfactory as an anti-agglomerant, 
since the ground Napalm is compacted into a 
solid mass after several days at 150 F, A few 
drums of the ground soap from regular pro¬ 
duction have been found to be agglomerated 
after storage at ambient temperature in the 
United States. However, since no complaints 
were received from the war theaters, the use 
of the ground soap can probably be considered 
a success. 

Thickened Fuels for hiceyidiaries. Napalm 
has been used extensively as a thickening agent 
for gasoline fillings for AN-M69 and AN-M47 
bombs. M69 bombs used 9 per cent Napalm, 
with a specification consistency range of 700 to 
1,100 g Gardner. Tests carried out by CWS 
Technical Command^ showed that consistencies 
of 500 to 1,100 gave satisfactory performance; 
the lower limit of 700 was set to allow for 
decrease of consistency on aging. The commonly 
used performance test for M69 bombs consisted 
in firing against a vertical plywood target and 
observing adhesion and scatter of the fuel. The 
peptized types of Napalm (those on the low 
side of the specification range) were found to 
give superior performance in this test, and at 
one time the use of peptized fuels in the M69 
was considered. This was abandoned because of 
the difficulty of setting up specifications and 
mixing such fuels reproducibly. 

The concentration of Napalm used in the M47 
bomb was 11.5 per cent, the higher consistency 
being required because of the greater shearing 
force applied to the fuel on the bursting of this 
bomb. 

Peptized Fuels. One of the earliest peptizers 
to be found useful was xylenol (and other 
phenolic compounds). With the use of this ad¬ 
ditive, it is possible to compound Napalm fuels 
at temperatures as low as zero F, whereas ordi¬ 
nary Napalm cannot be dispersed in gasoline 


in a reasonable time at temperatures lower than 
55 F. In addition, the incorporation of peptizers 
renders Napalm fuels less rigid and elastic, 
and more like ordinary liquids. Hence, at equal 
Gardner consistencies peptized fuel can be more 
readily poured into a flame-thrower fuel than 
regular Napalm and is less susceptible to 
channelling in the tank. Peptized fuels are more 
stable than regular Napalm, especially at low 
consistencies. Hence, if storage of the fuel for 
a long time were required, a 6 per cent fuel 
reduced in consistency to 100 g Gardner with 
alcohol, xylenol, etc., would be superior to a 4 
per cent Napalm without peptizer. For example, 
the consistency of a 4.5 per cent Napalm fell 
from 120 to 75 g Gardner in two months in a 
steel drum, and that of a 6 per cent Napalm 
containing 0.1 per cent ethyl alcohol, from 125 
to 105. 

At the request of the Infantry Board, a flame¬ 
thrower fuel was developed in an attempt to 
combine the principal advantages of unthickened 
and thickened fuels, i.e., fierceness of burning 
and long range, respectively.Flame-thrower 
shots with peptized and unpeptized fuels of 
various consistencies showed that the desired 
characteristics were most nearly attained at 
about 25 g Gardner. Ordinary 2.5 to 3 per cent 
Napalm fuels have about this consistency, but 
such fuels were considered undesirable because 
of long mixing time and poor keeping char¬ 
acteristics. After a series of tests with peptized 
fuels of 4 to 8 per cent Napalm, it was decided 
that a 4.2 per cent Napalm reduced to 25 g 
Gardner with either 0.5 per cent xylenol or 
0.05 per cent water should be satisfactory if 
long-time keeping were not required. These 
fuels were tested by the Infantry Board, and 
the one prepared with water (one 5i/4-lb can 
Napalm, two tablespoons water, 20 gal gaso¬ 
line) was adopted for uses for which a “brush 
flame” was desired. 

One important disadvantage of peptized fuels 
compounded with xylenol is their large increase 
in consistency with decrease in temperature. 
This is in contrast to regular Napalm gels, the 
consistency of which is relatively independent 
of temperature. Fuels peptized with water, on 
the other hand, decrease in consistency with 
decrease in temperature, and it has been found 





200 


FUELS FOR INCENDIARIES AND ELAME THROWERS 


possible, by using a mixture of xylenol and 
water, to obtain a peptized fuel the consistency 
of which is essentially independent of tempera¬ 
ture.^^ Very little work has been done on this, 
however, and it is probable that the propor¬ 
tions of xylenol and water required by different 
Napalms would vary considerably. The best 
single peptizers for low temperature coefficient 
of consistency are the alcohols."**^ If base mixing 
of flame-thrower fuels for shipping abroad 
should be undertaken, alcohol-peptized fuels 
would probably be most satisfactory from the 
standpoint of stability over the range of time 
and temperature which might be encountered. 

Super-Peptized Fuels. When the amount of 
water in a Napalm fuel is increased beyond ap¬ 
proximately one-tenth of the soap content, no 
appreciable further decrease in consistency 
takes place. Fuels compounded with excess 
water have been termed “minimum consistency” 
or “super-peptized” fuels. The obvious ad¬ 
vantage for such fuels, particularly in a humid 
climate, is that they are not affected by small 
additional quantities of water, as are regular 
Napalm fuels. One such fuel used fairly ex¬ 
tensively in the Pacific theater consisted of 13 
gal of gasoline, one 5i/4-lb can of Napalm, and 
11/2 qt of water, which corresponds to about 
6.3 per cent Napalm and 3.5 per cent water. 
A number of such fuels prepared from repre¬ 
sentative Napalms were found to have con¬ 
sistencies of 15 to 20 g^^^ and were quite stable 
at temperatures of 80 to 120 F. When these 
fuels are prepared and stored at 55 F, how¬ 
ever, the one-day consistencies are very much 
higher, 200 to 400 g, since the peptizing effect 
of water is retarded at low temperature. After 
one month storage at 55 F, the consistencies 
are lower than at room temperature, on account 
of the inverse temperature coefficient of con¬ 
sistency of water-peptized fuels. Hence, their 
use should not be recommended at low tem¬ 
peratures. 

Performance of the super-peptized fuels de¬ 
scribed above (15 to 20 g Gardner) in portable 
flame throwers is similar to that of other 
Napalm fuels of the same consistency, for ex¬ 
ample, the brush-flame fuel developed for the 
Infantry Board. Range in the air was 35 to 40 
yd, center of deposit on the ground, 40 to 50 yd. 


However, very little fuel reached the ground. 

In compounding these fuels in the field, par¬ 
ticularly if the drum and paddle method of 
mixing is used, it is essential that the water be 
first mixed with the dry Napalm before adding 
to the gasoline. If the water is first added to the 
gasoline and agitation is not violent, most of 
the water remains as a separate layer on the 
bottom, and the consistency of the resulting 
fuel may be two to four times what it would be 
if the water were evenly dispersed. 

Fuels Co7itaining Dehydrating Agents. In¬ 
corporation of moderately strong dehydrating 
agents such as silica gel, calcium chloride, and 
magnesium sulfate in Napalm fuels increases 
their consistency and stability. Fairly extensive 
tests have shown that silica gel is the most 
efficient agent in this respect.^*’ Magnesium 
sulfate is also quite satisfactory, but in most 
instances it does not produce so great an in¬ 
crease in consistency, and fuels compounded 
with it are not so stable as those containing 
silica gel. However, the total moisture capacity 
of the magnesium sulfate is greater than that 
of silica gel, making it somewhat superior in 
cases where water corresponding to more than 
about 20 per cent of the weight of the dehy¬ 
drating agent is introduced either during com¬ 
pounding or subsequently. 

Comprehensive tests with Napalm samples 
from a number of manufacturers have shown 
that incorporation of silica gel does not appre¬ 
ciably increase uniformity of consistency among 
the various Napalms, and that the increase in 
stability is not greater than would result from 
increasing Napalm concentration to give the 
same consistency.^® However, fuels compounded 
with silica gel (3 per cent Napalm + 2 to 4 
per cent silica gel) showed considerably greater 
resistance to the effect of such peptizers 
as xylenol, alcohol, acid soldering flux, amines, 
and potassium acetate. This is in keeping with 
previous experiments which had shown that 
certain Napalms could not be increased in thick¬ 
ening power by prolonged drying in a vacuum 
oven at 160 F, even though the incorporation 
of silica gel resulted in a large increase in con¬ 
sistency. This phenomenon may be accounted 
for by the adsorption of uncombined acid from 
the Napalm by the silica gel. It is this adsorp- 




NAPALM 


201 


tion of other polar compounds, in addition to 
water, which makes silica gel superior to mag¬ 
nesium sulfate as an additive to Napalm fuels. 

One possible drawback to the use of silica gel 
in Napalm fuels is the abrasive effect of the 
material on pumps which might be used in 
mixing, transferring or firing the fuel. In one 
case a high-speed Blackmer vane pump was 
ruined by 15 min recirculation of a fuel con¬ 
taining “thru 80” (actually, approximately 28 
to 200 mesh) silica gel. Another possible diffi¬ 
culty is that of uniformly dispersing the silica 
gel in the fuel by paddle mixing. This is some¬ 
what easier if the silica gel is added at about the 
stir time rather than at the beginning of mix¬ 
ing. 

Base mixing of flame-thrower fuels stabi¬ 
lized with silica gel has been recommended by 
the 43rd Chemical Laboratory Company in 
Hawaii.^^’ Considerable quantities of such 
premixed fuels were prepared by the 43rd 
Chemical Laboratory Company, but World War 
II ended before these fuels could be given a 
thorough trial in the field. The Company re¬ 
ported that the abrasive effect of the silica gel 
is negligible if the material is ground to 200 
mesh. This has been tentatively confirmed in 
unreported experiments at the Eastman Kodak 
Co. 

Fuels Containing Heavy Oils. Numerous re¬ 
ports of the incorporation of diesel oil, bunker 
C oil, or motor oil in Napalm fuels to retard 
the setting rate at elevated temperatures have 
come from the field. Because the specifications 
for diesel oil are less rigid than for gasoline, 
considerable variation in consistency can re¬ 
sult from its incorporation in thickened fuels. 
Incorporation of as little as 25 per cent of eleven 
representative diesel oils supplied by the Navy 
in 4 per cent Napalm fuels resulted in a con¬ 
sistency variation of 26 to 64 g, compared to 
a consistency of 61 for the fuel prepared with 
100 per cent motor gasoline. It was observed 
that diesel oils which were darkest in color 
had the greatest deleterious effect. 

Experiments conducted by CWS Technical 
Command showed that homogeneous fuels could 
be prepared with the fastest setting type of 
Napalm (Navy ground) at 100 F by first pre¬ 
paring a slurry of the Napalm in motor oil. 


The slurry is added through a coarse screen to 
the gasoline in the mixing drum, the volume of 
gasoline being reduced by the volume of oil 
added with the Napalm. Some motor oils con¬ 
tain additives which peptize Napalm, rendering 
the fuel too thin for use. Representative oils 
containing no such additives are Navy Symbol 
2190, 2250, 3050, 3065, and 3080. These oils 
have been checked in the laboratory and found 
not to affect the consistency of Napalm fuel. 
It is understood that one or more of them are 
available in large quantity on practically any 
ship. The effect on Napalm consistency of motor 
oil available to Army personnel is not known. 
However, motor oil has been used in the field to 
retard the setting of Napalm, its peptizing ac¬ 
tion probably having been compensated by in¬ 
creasing the Napalm concentration. 

Field Viscosimeters. As noted above, the 
Gardner consistencies of Napalm fuels serve as 
satisfactory guides to their performance in 
flame throwers, blaze bombs, and incendiaries. 
Since all fuels for incendiary bombs are mixed 
in the United States, the Gardner mobilometer 
is used for measuring their consistency. How¬ 
ever, fuels for flame throwers and blaze bombs 
are usually mixed in forward areas where 
mobilometers are not available, and probably 
could not be conveniently used if available. For 
this reason, considerable research has been 
carried out in an attempt to develop a simple 
viscosimeter for field evaluation of thickened 
fuels. 

An early attempt along these lines was a ball 
viscosimeter developed by Standard Oil De¬ 
velopment Co. and the Chemical Warfare Serv¬ 
ice. The ball viscosimeter consists of a trans¬ 
parent plastic tube, about 2 in. in diameter, and 
steel balls of six sizes, %2 in., %o in., %2 in., 
%2 in., %2 in., and i %2 in. in diameter. The di¬ 
ameter of the ball which falls through 10 cm 
of fuel in 30 sec is the measure of the viscosity 
of the fuel. Although it does not give perfect 
agreement with Gardner values, the instrument 
is quite useful in evaluating fuels between 20 
and 200 Gardner, these consistencies corre¬ 
sponding to the % 2 -in. and the 1 % 2 -in. balls, 
respectively. Further study showed that some¬ 
what better correlation with Gardner consist¬ 
ency is obtained if a fall time of 100 sec is used. 



202 


FUELS FOR INCENDIARIES AND FLAME THROWERS 


and the usable range of the instrument can be 
increased to 600 g Gardner by using balls up to 
1 in. in diameter. 

A simple viscosimeter which can be fabri¬ 
cated from materials available in the field has 
also been developed.This consists of a 
C-ration can with a I/ 4 .- or circular open¬ 

ing in the bottom and an additional C-ration 
can for catching the fuel passing through the 
opening. In operation, the viscosimeter can is 
filled with the fuel to be tested and placed not 
over 1 in. above the receiving can. The viscosim¬ 
eter can is kept full during the test by gradual 
addition of fuel from another container. The 
time required to fill the bottom can is a measure 
of the viscosity of the fuel. 

The 100 Gardner fuel commonly used in the 
portable flame thrower corresponds to about a 
% 2 -in. ball (100 sec fall time), or an efflux time 
of 15 min with the V 4 .-U 1 . orifice (1.5 min with 
the V-y-in. orifice). The 25-g consistency, which 
gives a brush flame, corresponds to a % 2 -iii- 
ball, or an efflux time of 1 min with the i/ 4 -in. 
orifice. The 200 to 250 g Gardner consistency 
considered optimum in the mechanized flame 
thrower corresponds to % 2 -fo-^% 2 -in. ball and 
an efflux time of 4 min with the Y-y-in. orifice. 
The 200 to 400 g consistency used in blaze 
bombs corresponds to ball. The 

upper limit, 400 g, cannot be satisfactorily 
evaluated with the efflux viscosimeter, but the 
minimum efflux time should be about 5 min with 
a 1 2 -in. orifice. If this is not attained with 6 per 
cent Napalm, 6.5 or 7 per cent should be tried. 
The probability of 6 to 7 per cent Napalm gel 
having a consistency greater than 400 g 
Gardner is very slight. 

Temperature Effects. The temperature co¬ 
efficient of viscosity of unpeptized Napalm fuels 
is small compared with that of ordinary New¬ 
tonian liquids. Fuels containing xylenol, how¬ 
ever, have much higher consistencies at low 
temperatures than at high; those containing 
water have lower consistencies at low tempera¬ 
tures. In each case the change is reversible, the 
fuel regaining its normal consistency on being 
returned to the higher temperature. There is 
no good evidence of any Napalm fuel having 
broken down, either by syneresis or by ab¬ 
normal reduction in consistency, on storage at 


low temperatures (down to —40 F). The nor¬ 
mal decrease in consistency, which occurs on 
aging at ordinary temperatures, is accelerated 
at elevated temperatures, and the consistency 
after one day at 150 F is ordinarily considered 
to be the minimum consistency which will be at¬ 
tained on aging at ordinary temperatures. This 
is not necessarily true, however, since several 4 
per cent Napalms, which had higher consist¬ 
encies after one day at 150 F than after one day 
at 77 F, showed the normal decrease in con¬ 
sistency on aging at ambient temperature. The 
explanation for the increase in consistency at 
elevated temperature is given by a Napalm 
substitute containing 80 per cent coconut oil 
acids and 20 per cent oleic acid which had a 
consistency of 1,100 after storage at 150 F, as 
compared to 430 at 77 F."’^ Aluminum soaps of 
coconut oil acids cannot be dispersed in gasoline 
at 77 F, and the proportion of oleic acid used 
in this mixture was not enough to cause total 
dispersion. Thus, storage at 150 F has two 
opposite effects, one tending to increase consist¬ 
ency, the other to decrease it, and in certain 
cases the net effect may be an increase. 

The effect of storage of Napalm gels at 120 F 
for one day to thirty-two days is shown in ref¬ 
erence 12. In general, most of the decrease in 
consistency occurs in one day or two days at 
this temperature, in contrast with a more grad¬ 
ual decrease over the entire 32-day period at 
70 F. The final, 32-day, consistency of 4 per 
cent gels was lower at 120 degrees than at 70 
degrees, which indicates that the aging effect is 
predominant over the dispersion effect at 120 
degrees. 

An interesting phenomenon occurs when reg¬ 
ular Napalm fuels are mixed and stored at 50 to 
60 F, approximately the minimum temperature 
at which Napalm can be dispersed without a 
peptizer. Setting rate of the Napalm is greatly 
retarded and maximum consistency is not at¬ 
tained until two to four days after mixing. 
This maximum consistency, however, is very 
much higher than that attained at 80 F. For 
example, a 2 per cent gel may have a consistency 
of 80 g instead of 10 g, a 4 per cent may have 
a consistency of 250 instead of 100. On con¬ 
tinued storage at 55 F, the consistency is still 
higher than normal after two months, although 


^NFIDEKTIAL^I} 





NAPALM 


203 


it begins to decrease after a weekd^ This ab¬ 
normal consistency is a result of retarded pep¬ 
tizing action of the water and uncombined acids 
in the Napalm at low temperature. If one of 
these fuels is brought to 80 F for only an hour, 
its consistency is found to be normal, even after 
being returned to the lower temperature. 

The difference in flame-thrower performance 
between these abnormal fuels and ordinary 
fuels of the same Napalm concentrations is not 
so great as would be expected on the basis of 
consistency. In fact, the concentration seems to 
be a more reliable guide to performance than 
the consistency, this being the most striking 
exception to the rule that consistency, irrespec¬ 
tive of concentration, determines performance. 
Gardner consistencies of these fuels, determined 
immediately after unignited firing from a flame 
thrower, show that their poor performance is 
due to mechanical breakdown of consistency in 
the gun. The “healing rate” at this low tem¬ 
perature is greatly retarded, but the material 
gradually returns to its abnormal consistency 
over a period of hours. 

Examination of the data for the blaze-bomb 
fuels mixed at Llandarcy^' shows that most of 
the fuels were mixed in the winter and that the 
gasoline temperature was generally in the range 
of 50 to 60 F. This accounts for the initial high 
consistency of th*ese fuels, many being 500 to 
600 g Gardner, and for the decrease in consist¬ 
ency which occurred on aging, the normal con¬ 
sistencies of 200 to 400 being attained in 2 to 3 
months. 

Another interesting temperature effect is ob¬ 
served on storing Napalm soaps at 150 to 160 F 
in hermetically sealed containers. Thickening 
power of representative Imperial Napalms in¬ 
creases from approximately 75 Gardner, for 
4 per cent gels, to 150 to 200 in two weeks at 
the elevated temperature. This increase in con¬ 
sistency is accompanied by an increase in mois¬ 
ture content and a decrease in extractable acid. 
This indicates that some of the uncombined 
acid combines with alumina or mono-soap, 
watei- being produced by the reaction. Decrease 
in extractable acid is of the order of 2 to 3 per 
cent on the basis of total soap. Why this should 
result in such a large increase in thickening 
power is not clear. On continued storage at 


160 F, the thickening power begins to decrease 
but is still above normal at sixteen weeks. 

Storage at 120 F has comparatively little 
effect on the thickening power of Napalm in 
twelve weeks, which indicates that exposure to 
temperatures which will ordinarily be encoun¬ 
tered should not be expected to materially 
change the thickening properties of the soap. 


' Substitute Napalm Formulas 

As a result of what appeared to be an immi¬ 
nent shortage of naphthenic acids,-"*- work was 
undertaken to develop a Napalm formula in 
which the naphthenic acid would be eliminated 
or its percentage materially reduced. After 
soaps of various acid ratios and excess caustic 
content were made up and tested, it appeared 
that the optimum composition, in the absence 
of naphthenic acid, was 80 per cent oleic and 
20 per cent coconut oil acids precipitated at an 
excess caustic ratio of 30 per cent.-"*^ High ratios 
of coconut oil acids produce soaps which are not 
completely dispersible in gasoline at room tem¬ 
perature and gasoline gels which tend to be 
short and crumbly. Low ratios of coconut oil 
acid produce soaps which become gummy on 
drying. In addition, soaps of over 80 per cent 
oleic acid tend to form thick, clear jellies on 
cooling, which makes the precipitation of 
straight aluminum oleates from concentrated 
soap solution unsatisfactory. However, this 
tendency is eliminated for all practical purposes 
by 10 to 20 per cent coconut acid. High basicity 
(60 per cent excess caustic) produces soaps 
which are too high in thickening power 
(greater than 800 g Gardner). 

The setting rate of the substitute containing 
80 per cent oleic acid is somewhat faster than 
regular Napalm for corresponding particle 
sizes. In addition, the average particle size of 
the substitute is smaller than that of the regu¬ 
lar Napalm; hence the overall tendency is for 
considerably faster setting. The length and 
healing rate are comparable to regular Napalm. 
The amount of alpha-naphthol required to pre¬ 
vent oxidation is directly proportional to the 
oleic acid content. 

Several formulations containing reduced 


CONFIDENTIAL ^ 









204 


FUELS FOR INCENDIARIES AND FLAME THROWERS 


quantities of naphthenic acid were also made up 
and tested. With respect to gel strength, crum¬ 
bliness, and setting rate these formulations are 
all between regular Napalm and the aluminum 
oleates. It was decided to retain 5 per cent 
naphthenic acid in order to utilize the available 
supply of the three acids, and several full-scale 
batches containing 65 per cent oleic, 30 per cent 
coconut, and 5 per cent naphthenic acids were 
prepared by the manufacturers. No serious diffi¬ 
culties were experienced in any of the plant 
operations. The substitute material was tested 
by CWS Technical Command in M69 and M47 
incendiary bombs and was reported to be com¬ 
pletely satisfactory. Because of the fast setting 
of the material, it is felt that additional re¬ 
frigerating capacity for cooling the gasoline 
might be required in some of the filling plants. 
However, before production could be shifted to 
the substitute formula, the naphthenic acid 
supply situation eased, and shortly thereafter 
World War II ended. 


^ Other Aluminum Soap Thickeners 

While research in the United States has been 
concentrated on improving Napalm with re¬ 
spect to uniformity, reliability, etc., numerous 
other aluminum soap thickeners have been de¬ 
veloped in Great Britain.These include (1) 
Brascon, a preformed concentrate of aluminum 
stearate peptized with cellosolve; (2) chan and 
chol, aluminum naphthenate and aluminum 
oleate, respectively, prepared by a direct reac¬ 
tion process; and (3) Camgel, consisting of two 
liquids; namely, aluminum cresylate solution 
and oleic acid, or a fatty acid solution. When 
mixed in gasoline these form the aluminum soap 
of the fatty acid. 

Research in the United States has shown 
that chan and Camgel could be produced here 
if desired. The former is of little interest be¬ 
cause of the naphthenic acid supply situation, 
but the latter is especially attractive because of 
the ease of mixing liquid components (see Sec¬ 
tion 8.3). 

Other aluminum soap thickeners which have 
been produced in quantity are: (1) Metalex, an 


aluminum soap of stearic and naphthenic acids 
peptized with cresylic acid, produced in New 
Zealand, and (2) geletrol, an aluminum soap of 
oleic acid, produced in Australia. 


8 3 LIQUID THICKENING AGENTS^^ 

® ^ ^ Aluminum Cresylate 

This two-liquid thickening agent, known as 
Camgel in England, was developed as a result 
of a suggestion of A. E. Alexander of Cam¬ 
bridge University. The aluminum soaps are 
formed in situ by metathesis between aluminum 
cresylate solution and oleic acid (or a solution 
of a fatty acid) when the two are mixed in the 
gasoline. The aluminum cresylate is prepared 
by heating cresol with aluminum foil in a suit¬ 
able solvent such as coal tar naphtha or kero¬ 
sene, etc. Properties of the fuel are dependent on 
the ratio of aluminum cresylate to fatty acid, 
and are improved by the inclusion of such addi¬ 
tives as methyl alcohol, cresol, water, and ace¬ 
tone. These peptizers are commonly incorpo¬ 
rated in the fatty acid solution, thus limiting 
the number of liquid additives to two. 

Because of the attractiveness of liquid thick¬ 
eners for the continuous mixing of thickened 
fuels, particularly for blaze bombs, considerable 
work has been done in the United States on 
aluminum cresylate.^i- it was shown that a 
satisfactory thickener could be manufactured 
from petroleum cresylic acids, the largest avail¬ 
able source, and that refined lubricating oil 
could be used as the solvent, in order to reduce 
the fire hazard for storage on aircraft carriers. 
Some excess cresol must be incorporated in the 
lubricating oil solution for the sake of fluidity. 

Tests of aluminum cresylate solutions from 
two NDRC laboratories and from PWD in 
Great Britain confirmed their essential equiva¬ 
lence, when the same amounts of aluminum 
cresylate and fatty acid are used. Optimum fuel 
characteristics are obtained with mixtures cor¬ 
responding to 1.7 to 2.2 molecules of fatty acid 
per molecule of aluminum cresylate. Setting rate 
can be accelerated wfith water, or decelerated 
with cellosolve, the latter additive greatly in- 



METHACRYLATE THICKENING AGENTS 


205 


creasing the stability of the fuels. When the 
cresylate solution contains about 0.5 g alumi¬ 
num cresylate per cu cm, the total additives 
required to produce a blaze-bomb fuel are 10 to 
12 per cent by volume. 

Because of the satisfactory performance of 
the Navy mixer with ground Napalm, aluminum 
cresylate was never produced in quantity. It 
was considered that this could be done if re¬ 
quired. 

Aluminum Alcoliolates 

Numerous alcohols and phenols, in addition 
to cresol, can be used in the preparation of 
liquid thickeners.A very satisfactory thick¬ 
ener has been made by Harshaw Chemical Co. 
with mixtures of sec-butyl and isopropyl alcohol. 
An 80 per cent solution of this alcoholate in lu¬ 
bricating oil is fluid. The alcoholate is superior 
to cresylate in that the total additives required 
to produce a blaze-bomb fuel are only 5 to 6 per 
cent by volume (approximately 1.5 per cent 
alcoholate solution) 4 per cent acid mixture. 

® Sodium Aluminate 

This thickener was developed at Harshaw 
Chemical Co. by Capt. John A. Southern of 
CWS.^^ One solution consists of sodium alumi¬ 
nate, sodium hydroxide, and water. The other is 
a special acid mixture of the following composi¬ 
tion : 3 parts coconut fatty acids, 1.5 parts oleic 
acid, 1.5 parts naphthenic acid, 2 parts ricin- 
oleic acid, and 0.25 part triethanolamine. The 
aluminate solution is prepared by suspending 
200 g sodium aluminate and 500 g sodium hy¬ 
droxide in enough water to make 1,000 cc and 
drawing off the clear solution after standing. 
Eight per cent of the acid mixture and 3.25 per 
cent sodium aluminate solution stirred briefly 
in gasoline produces a gel of the desired con¬ 
sistency. Prolonged stirring reduces consist¬ 
ency, and the gel does not tend to heal. It is 
much less stringy than Napalm, but it might be 
satisfactory in blaze bombs. The ease of manu¬ 
facture and freedom from fire hazard of the 
aluminate solution make it particularly attrac¬ 
tive. 


Valoiie 

Equimolecular quantities of 2-valeryl-l,3-in- 
dandione (Valone) and 72-monododecylamine 
produce a gel when mixed in gasoline. Solutions 
of the individual components in gasoline may 
be used, but a more interesting application is 
the solution of the two in tetrachloroethane. A 
50 per cent solution (25 per cent Valone, 25 per 
cent amine) is a mobile liquid, and 10 per cent 
of the solution forms a thick gel in gasoline. 
This gel, like that from sodium aluminate, is 
lacking in stringiness, but is of particular inter¬ 
est because of the single-liquid additive. All the 
two-liquid thickeners must be mixed in the cor¬ 
rect proportions in order to be effective, thus 
requiring rather complicated mixing equipment. 
With a one-liquid thickener this problem is 
greatly simplified, the present Navy (injector) 
mixer, or a similar device, being adequate. In 
addition, the tetrachloroethane solution is non- 
inflammable. 

It has been found that amines of coconut 
fatty acids, available commercially, and crude 
Valone, which can be produced in large quan¬ 
tities, thicken gasoline as satisfactorily as the 
pure substances. 


» ^ METHACRYLATE THICKENING 
AGENTS"' 

Introduction 

A number of synthetic and natural polymers 
were investigated as possible thickening agents 
for gasoline for use in various incendiary bombs 
and flame throwers. Rubber had been investi¬ 
gated for this purpose in 1941 and had proved 
quite good, but after Pearl Harbor there was 
no rubber available for these uses. By the time 
synthetic rubber was available in sufficient 
quantities, other thickening agents had been 
developed which were entirely satisfactory for 
these uses. Among the synthetic polymers in¬ 
vestigated, the most successful was isobutyl 
methacrylate polymer fortified with certain 
sodium soaps. Thickening agents of this type 
were used extensively during 1942 and 1943 for 



206 


FUELS FOR INCENDIARIES AND FLAME THROWERS 


filling AN-M47 and AN-M69 incendiary bombs, 
and they could have been used for flame-thrower 
fuels if Napalm had not been available and 
more convenient for field mixing. 

The E. 1. duPont de Nemours & Co., Ammonia 
Department, had cooperated with the Chemical 
Warfare Service during January to April 1942, 
in the development of a synthetic polymer thick¬ 
ening formula for filling the AN-M47 100-lb oil 
incendiary bomb. The result was the following 
formula. 


IM Type I 

Isobutyl methacrylate polymer AE 5 % 

Stearic acid 3% 

Calcium oxide 2% 

Water 1.25% 

Gasoline 88.75% 


This filling was used extensively for filling 
AN-M47 bombs during 1942 and part of 1943 
when it was replaced by IM Type IV (see 
page 207). 

In May 1942 duPont was invited to cooperate 
on an informal basis with the NDRC-Standard 
Oil Development Co. group in developing an 
isobutyl methacrylate polymer formula for fill¬ 
ing the new AN-M69 bomb. The result was the 
following formula.^" 


IM Type II 

Isobutyl methacrylate polymer NR 5% 

Hydrofol 51 (stearic acid) 2.5% 

Naphthenic acid 2.5% 

Aqueous solution of caustic soda (40%) 3% 

Gasoline 87% 


The filling was compared with other competi¬ 
tive gasoline gels in a series of tests in May 
1942 with the result that IM Type II was 
adopted for use in the initial production of 
AN-M69 bombs. IM Type II was replaced by 
IM Type III in March 1943 (see page 207). 

The code letters AE and NR stand for Ar¬ 
senal Edgewood and National Research, respec¬ 
tively. Polymer AE was a much higher average 
molecular weight than polymer NR, although 
the actual molecular weight was not known for 
either one. 

After the above developments a formal con¬ 
tract was made with E. 1. duPont de Nemours 
& Co., Ammonia Department (OEMsr-744), 
beginning August 1, 1942, for the purpose of 
studying the several variables involved in these 


formulas and of developing either better for¬ 
mulas, or satisfactory formulas requiring less 
of critical materials such as isobutyl methacry¬ 
late and naphthenic acid. The remainder of this 
section describes the results obtained under this 
contract. 


® Laboratory Studies 

The study of gasoline gels thickened by 
polymers is reviewed by summarizing the effect 
on gel properties of varying, in turn, the nature 
and concentration of each of the basic gel com¬ 
ponents. 

Co7iclusionsS'- Gel preparation usually in¬ 
volves preparation of a low-viscosity gasoline 
solution containing isobutyl methacrylate poly¬ 
mer and soap-forming acids which are gelled 
or thickened by the addition of a small amount 
of aqueous alkali. In general, the polymer de¬ 
termines strength characteristics, while the 
soap ingredients contribute body to these mix¬ 
tures. 

1. The range of strengths required of gels 
for the various incendiary munitions was cov¬ 
ered by using NR or AE grade isobutyl metha¬ 
crylate polymer for the weaker gels, and one of 
a series of interpolymers of isobutyl methacry¬ 
late and methacrylic acid for the strongest gels. 
Polymer content of soap-fortified gels varied 
from 1 to 10 per cent. The minimum polymer 
contents consistent with stability and the de¬ 
sired gel strengths were determined. 

2. A large number of soap-forming acids were 
assessed as gel bodying agents. Formulation of 
the six most effective acids was intensively 
studied in gels containing various combinations 
of two or three acids. Of these six acids, stearic 
and oleic acids impart stiffness, body, and high- 
temperature stability to all types of methacry¬ 
late gels. Naphthenic acid and dimerized soy¬ 
bean oil acids act as gel plasticizers, while rosin 
and Turkey-red oil normally function as plas¬ 
ticizing agents but occasionally fulfill both of 
the above-described functions. The most effec¬ 
tive acid combinations are stearic acid-naph¬ 
thenic acid; stearic acid-naphthenic acid-wood 
rosin; stearic acid-dimerized soybean oil acid; 
and stearic or naphthenic acids alone. 



METHACRYLATE THICKENING AGENTS 


207 


3. To study the effect of the gelation agent, 
strong and weak bases were tested at various 
ratios of acids to base to water. Only strong- 
bases caused effective gelation. The use of 
aqueous sodium hydroxide, ground lime, and 
calcium hydroxide was studied in detail. Unsuc¬ 
cessful attempts were made to prepare stable 
gels with ammonia or amines. 

4. Stiffness and a reduction in resilience were 
imparted to strong, fluid gels containing iso¬ 
butyl methacrylate-methacrylic acid interpoly¬ 
mers by the addition of inert solid materials. 
Ground alpha-cellulose was the most effective 
filler tested. 

5. Other NDRC research groups studied the 
gasoline requirements of methacrylate gels and 
concluded that an aniline point below 105 F 
was required to obtain gel stability. 

Physical Measurements.'^- The physical prop¬ 
erties of various gels were compared with the 
results of field evaluations, and the sensitivity 
of various tests to minor changes in composi¬ 
tion of a given gel formula were determined. 
To obtain significant characterization of metha¬ 
crylate gels, it was necessary to modify existing 
methods and to develop new techniques. New 
physical measurements developed under this 
contract include the impact strength, parallel 
plate, and burning rate tests. The impact 
strength, a measurement of consistency at a 
high shearing force, was useful in gel research 
to predict behavior of diverse gel formulas in 
static firing tests of incendiary bombs. The 
parallel plate test, a measurement of body un¬ 
der a low shearing force, was adapted to plant 
control on specific gel formulas, where it 
showed excellent sensitivity to quality of in¬ 
gredients and method of compounding. The 
burning rate test gave a comparative measure 
of the incendiary characteristics of diverse gels. 

The stability to exposure to both high and 
low temperatures of gels prepared during the 
formulation study was determined and has been 
correlated with gel composition. 

Neiv Gel Formulas.''"’ As a result of the 
studies made by duPont under Contract 
OEMsr-744, the following formula was selected 
to replace IM Type II for filling AN-M69 bombs 

This formula went into production in March 
1943, replacing IM Type II for filling AN-M69 


IM Type III 


Isobutyl methacrylate polymer AE 

2% 

Hydrofol 51 (stearic acid) 

3% 

Naphthenic acid 

3% 

Aqueous solution of caustic soda (40%) 

4.5% 

Gasoline 

87.5% 

bombs, and still later it was replaced by Napalm 

for this purpose. 


The following formula was selected to replace 
IM Type I for filling AN-M47 bombs.'^"’ 

IM Type IV 


Isobutyl methacrylate polymer AE 

3% 

Stearic acid 

4% 

Calcium oxide 

4% 

Water 

2.5% 

Gasoline 

86.5% 


In this formula 3 per cent additional calcium 
stearate replaces 2 per cent of isobutyl metha¬ 
crylate polymer in IM Type I, giving an equiva¬ 
lent gel. IM Type IV was later replaced by 
Napalm for filling AN-M47 bombs. 

Isobutyl Methacrylate Interpolymer Formu- 
las.'^^’ An interesting series of gels were de¬ 
veloped containing both isobutyl methacrylate 
polymer and free methacrylic acid, but no 
stearic or naphthenic acids. A typical formula 
would be: 

Isobutyl methacrylate polymer AE 3 to 6% 
Methacrylic acid 0.1 to 0.3% 

Aqueous solution of caustic soda (40%) 1% 

Gasoline 93 to 96% 

Such gels gave strengths equal to IM Types I 
to IV, and contained materially higher per¬ 
centages of gasoline, the primary incendiary 
material. Apparently, the free methacrylic acid, 
which contains a double bond, forms cross link¬ 
ages similar to those in vulcanized rubber, 
thereby imparting high gel strength with a rela¬ 
tively small percentage of gelling agent. At 
first these gels were not sufficiently stable at 
low temperatures, but this was later corrected 
by good control of compounding. Although this 
type of gel looked attractive it was never used, 
since in the meantime Napalm had been per¬ 
fected and dominated the field of thickening 
agents. Methacrylate interpolymer gels were 
particularly good when made with a fuel con¬ 
taining around 20 per cent of toluene. 

Other Polymers. In a search for isobutyl 
methacrylate substitutes, a study of other com¬ 
mercial resins was undertaken. A search for 






208 


FUELS FOR INCENDIARIES AND FLAME THROWERS 


gasoline-soluble polymers other than metha¬ 
crylates revealed only the polyvinyl ethers, 
Vistanex (polyisobutylene) and the rubber sub¬ 
stitutes derived from vegetable oils. Satisfac¬ 
tory strength in gels containing the latter two 
materials was obtained only when the polymer 
content exceeded 10 per cent. The polyvinyl 
ether procured from the General Aniline & Film 
Corp. was tested as a direct substitute for 
polyisobutyl methacrylate and as a constituent 
of soap-free gels. The properties of polyvinyl 
ether gels are comparable to those prepared 
from methacrylate polymers. Evaluation of 
these mixtures as flame-thrower fuels has been 
undertaken by other NDRC groups. Gel prep¬ 
aration was attempted with other commercial 
resins, especially ethyl cellulose, by adding an 
auxiliary solvent to the gasoline. It was con¬ 
cluded that without further modification such 
polymers do not impart sufficient strength to 
gasoline-soap gels and that the use of a water- 
miscible auxiliary solvent results in poor gel 
stability at high temperatures. 

Modification of existing commercial resins 
and the synthesis of new polymeric gasoline 
thickening agents was “high-spotted.” While 
several gasoline-soluble cellulose and vinyl res¬ 
ins were prepared, degradation occurred during 
the introduction of functional groups so that 
only low molecular weight materials were ob¬ 
tained. 


Preparation of Gels 

Batch Pre'parationS’- The basic method of pre¬ 
paring methacrylate gels involves adding an 
aqueous solution of a base, such as sodium hy¬ 
droxide, to a stock solution consisting of polymer 
and soap-forming acids dissolved in gasoline. 
The stock solution is prepared by dissolving 
first the acids, then the polymer, with strong 
agitation in the gasoline. To insure solubility 
of stearic acid, the gasoline temperature must 
exceed 12 C. When mixtures of acids were used 
it was found convenient to weigh the acids into 
a container heated on a steam bath or, when 
rosin was present, on an electric heater, and to 
add the molten mixture to the gasoline while 
stirring. Solution of polymer was most readily 
obtained by adding the entire amount required 


at one time. Stirring was continued until solu¬ 
tion was complete. Fillers were sometimes 
added to this stock solution. Gelation was ob¬ 
tained by pouring the aqueous basic solution 
rapidly into this stock solution while stirring 
with an electrically driven stirrer. Agitation 
was continued for 1 min or until the mixture 
had sufficiently gelled to climb the shaft of the 
stirrer. The usual size of a laboratory batch 
was 400 g prepared in a wide mouth, 1-qt bottle. 
The gels were allowed to set in the closed con¬ 
tainer at least 24 hr before examination. 

When lime was used as the gelling agent, the 
powdered dry lime was dispersed in the stock 
solution and water was then added to effect 
gelation. These mixtures were stirred at least 2 
min after the addition of water. Since the par¬ 
ticle size of the lime affected the rate of gela¬ 
tion and the final properties of the gel, a stand¬ 
ard mixture was obtained by crushing USP 
lime, screening, and compositing the fractions 
to give a mixture with the following screen 
analysis. 


35 to 60 mesh 

22% 

60 to 80 mesh 

22% 

80 to 100 mesh 

22% 

100 to 120 mesh 

22% 

Through 200 mesh 

12% 


100 % 


This synthetic mixture has a screen analysis 
which is the average of several analyses on 
limes ground to pass 40 mesh. 

Pilot Plant Continuous Preparation. For 
larger than laboratory scale preparation of 
methacrylate gels it seemed desirable to develop 
a continuous rather than a batchwise process. 
Gelation involves rapid intimate mixing of a 
gasoline stock solution containing polymer and 
soap-forming acids with the aqueous caustic 
solution. In preliminary tests the mixing ob¬ 
tained by injecting the two streams into a cen¬ 
trifugal pump seemed more controllable than 
the mixing obtained by passing the two solu¬ 
tions under pressure simultaneously through an 
orifice. The small-scale unit shown diagram- 
matically in Figure 1 was therefore assembled. 
The stock solution is prepared batchwise in 
holdup tank T-1 while the 40 per cent caustic 
solution is stored in tank T-2. These solutions 
are drawn from the tanks at calibrated rates by 




CELLULOSE-BODIED FUELS 


209 


metering gear pumps. The two metered streams 
join in a tee or Y which immediately precedes 
the inlet to the centrifugal mixing pumps. Shut¬ 
off and sampling valves are so located that the 
rate of flow of each stream can be calibrated 


FLOWSHEET 



DRAIN AND 
SAMPLE LINE 

Figure 1. Continuous unit for the preparation of 
methacrylate gels. 

separately. The gel produced in the mixing 
pump is forced through the discharge line and 
loaded directly into a bomb or container. The 
maximum production of the experimental unit, 
limited by pump capacity, was 10 lb of IM-II 
gel per min. At this rate the back pressure de¬ 
veloped in the discharge line, which was 15 ft 
of standard 1-in. black iron pipe, including two 
90-degree bends, was 5 psi. 

To obtain the flexibility required for experi¬ 
mental studies, all three pumps were operated 
by variable speed drives. In the unit producing 
IM-II and IM-III gel at the Kilgore Manufac¬ 
turing Co., it was found advantageous to oper¬ 
ate both metering gear pumps from the same 
driveshaft, and to predetermine the ratio of 
the two streams by the proper choice of gears 
coupling the pumps to the shaft. 

8 5 SODIUM SOAP THICKENING AGENTS'’'^-«« 

Before the advent of Napalm and isobutyl 
methacrylate thickening agents for gasoline, a 
considerable amount of work was carried out on 


formulas using various sodium soaps as the 
principal gelling agent.“5. «« These formulas con¬ 
tained the following compounds: (1) a fatty 
acid which may be stearic acid, hydrogenated 
fish oil acid, tallow acid, oleic acid, or cotton¬ 
seed oil acid; (2) resin; (3) a plasticizer which 
may be isopropyl alcohol, cottonseed oil, castor 
oil, fish oil, rapeseed oil, stearine, or glycerine; 
(4) sodium hydroxide solution; and (5) gaso¬ 
line, kerosene, or both. 

Hundreds of different formulas were tried. 
On the basis of burning rate, stability, avail¬ 
ability of materials, and ease of preparation, 
the following formulas were considered to be 
fairly good, although even better formulas 
might have been worked out: 



SOD 

SOD 

SOD 


formula 

formula 

formula 


122 

392 

433 

Stearic acid 

3.5% 

4.5% 

3.5% 

Resin 

1.75% 

2.25% 

1.75% 

Castor oil 

3.0% 



Sulfonated cottonseed oil 


0.2% 

0.2% 

Stearine 



3.0% 

Sodium hydroxide 

2.0% 

0.8% 

2.0% 

Water 

2.0% 

0.8% 

2.0% 

Gasoline 

81.25% 

83.2% 

81.05% 

Kerosene 

6.5% 


6.5% 


These formulas were found to perform quite 
well in the AN-M69 bomb, although they were 
not suitable for the AN-M47 or other bursting 
type bombs on account of their low cohesive¬ 
ness, compared to the NP and IM types of gels. 
Burning tests in incendiary-test structures 
showed that the sodium soap gels were not 
quite as good as NP and IM gels even in the 
AN-M69 bomb because of their greater breakup 
on ejection. Therefore the sodium soap gels 
were discarded and were never used in produc¬ 
tion of AN-M69 bombs. They were sufficiently 
satisfactory, however, and might have been used 
if a serious shortage of NP and IM had devel¬ 
oped during World War 11. 


8 CELLULOSE-BODIED FUELS®' 23. ct-ts 

In addition to gasoline gel fuels, fuels bodied 
with cellulose wadding (cellucotton) appeared 
quite promising for use in incendiary bombs. 
They might also possibly have been used in 
some types of flame throwers, but could obvi- 



















210 


FUELS FOR INCENDIARIES AND FLAME THROWERS 


ously not be used in conventional types. A fuel 
consisting of 13 per cent cellucotton and 87 per 
cent gasoline gave very good results in the 
AN-M69 bomb. The cellucotton simply soaks up 
the gasoline even though the gasoline weighs 
almost seven times the cellucotton. 

Cellucotton-gasoline fuels have the following 
advantages over gelled fuels: 

1. Stabilitij. There is no question of the short 
or long term stability of this fuel, whereas sta¬ 
bility was a major difficulty in the early devel¬ 
opment and production of Napalm. 

2. Simplicity of production. This applies par¬ 
ticularly to the factory filling of incendiary 
bombs. 

3. lgnitio7i. Ignition would be no problem 
with this fuel, whereas low-temperature igni¬ 
tion was always a problem with gelled fuels. 

4. Temperature effect. Cellucotton-gasoline 
fuels would have nearly the same performance 
at all temperatures, whereas the performance 
of gelled fuels varied with temperature. 

5. Fuel distribution. With cellucotton-bodied 
fuels it is possible to have a uniform, predeter¬ 
mined size of fuel chunks, whereas with gelled 
fuels the chunks varied very greatly in size, and 
shattering was always more or less a problem. 

6. Availability. There would be no supply 
problem in the case of cellucotton, whereas con¬ 
stituents of both Napalm and methacrylate 
were in short supply throughout World War II. 

7. Cost. Cost of filling bombs with these fuels 
would be much less than for gelled fuels. 

Comparative burning tests of cellucotton- 
gasoline fuels in AN-M69 bombs against vari¬ 
ous incendiary-test structures indicated these 
fuels to be approximately equivalent to the same 
weights of gelled fuels. One disadvantage was 
the greater tendency of cellucotton fuels to 
bounce olf target surfaces and lack of tendency 
to adhere. However, gelled fuels also bounce off 
surfaces in striking at small angles, and a 
thoroughgoing comparison was never made on 
this point. 

The controlled size of fuel chunks would be a 
matter of minor importance in the AN-M69 
bomb, but it might have been very important 
for bursting-type bombs, such as the AN-M47 
and AN-M76. The E22, 500-lb tail ejection 
bomb, developed by Factory Mutual Research 


Corp., used a cellucotton-bodied fuel with very 
promising results. 

In spite of the attractive features of the 
cellucotton-bodied fuels, they were never used 
in World War II primarily because the gelled 
fuels got started first. Cellucotton fuels were 
never tested for use in flame throwers primarily 
because the whole emphasis was on conven¬ 
tional nozzle-type flame throwers. 

»- FORTIFIED FUELS-'- 

‘ Introduction 

Numerous fuels in which hydrocarbons were 
fortified by the addition of combustible metals 
and oxidizing agents, or by the addition of 
either one, were investigated during World 
War II and proposed for use in incendiary 
bombs and flame throwers. The heat outputs 
of the standard gasoline gel fuels were quite 
satisfactory for use in incendiary bombs and 
flame throwers, but they had the drawbacks of 
burning at comparatively low temperatures and 
of being easily extinguished by water. It was to 
correct these two drawbacks that fortified fuels 
were investigated by NDRC, the Chemical War¬ 
fare Service, and by the British Petroleum War¬ 
fare Department. However, their use in the 
war was very limited, largely in the M74 and 
AN-M76 incendiary bombs, which were devel¬ 
oped by the Chemical Warfare Service. NDRC 
work on fortified fuels was principally in con¬ 
nection with the development of the E9 and E19 
incendiary bombs. 

The principal advantages to be expected 
from fortified fuels are outlined below. 

1. Higher temperature and greater fierce¬ 
ness of burning. This property is of interest in 
both incendiary and anti-personnel applica¬ 
tions. 

2. Less easily extinguished by water. This 
property is primarily of interest in incendiary- 
bomb applications. 

Other less important advantages of fortified 
fuels are (1) greater range in flame throwers 
resulting from higher densities, and (2) pro¬ 
duction of irritant gases such as sulfur dioxide. 

Since all fortifying additives have higher 








FORTIFIED FUELS 


211 


densities than hydrocarbons, the densities of 
fortified fuels are always higher than gasoline 
gels. The heat outputs per unit weight of for¬ 
tified fuels are lower than gasoline gels, but 
the higher density offsets this, so that the heat 
outputs per unit volume are usually about the 
same as gasoline gels. These facts constitute 
a net disadvantage for fortified fuels when 
weight is a critical factor as it sometimes is 
both in incendiaries and in flame throwers. An¬ 
other disadvantage of fortified fuels is their 
generally lower degree of cohesiveness (greater 
shortness). 

The following sections describe only NDRC 
work in this field. The formulas given are rep¬ 
resentative of a much larger number described 
in the original references. 


« “ 2 Hvdrocarboii-Metal-Oxidiziiig Agent 
Mixtures'-- 

^Mixtures under this heading constitute the 
most important fortified fuels investigated by 
NDRC. Most of these were investigated by Fac¬ 
tory IMutual Research Corp. in connection with 
the E19 incendiary bomb, or by the Texas Co. 
in connection with the E9 incendiary bomb. 
Following are some representative formulas. 

1. 25% Motor oil (SAE40) 

35% Aluminum powder 
40% Sodium nitrate 

This mixture has a heat output of 8,930 Btu per 
lb and a density of 1.50, which puts it on a 
par on a volume basis with gasoline gel which 
has a heat output of about 17,500 Btu per lb 
and a density of 0.78. 

2. 20% Motor oil (SAE40) 

10% Asphalt 

15% Aluminum powder 
55% Sodium nitrate 

3. 35% Lubricating grease 
15% Aluminum powder 

5% Sulfur 
45% Sodium nitrate 

This mixture has a heat output of 7,800 Btu per 
lb and a density of 1.54. 

4. 7.1% Motor oil (SAE40) 

14.8% Aluminum flake 

1.6% Sulfur 


14.8% Sodium nitrate 
11.7% Barium nitrate 
50.0% Thermite 

Mixtures 1, 2, and 3 were preliminary formulas 
developed for the E19 incendiary bomb, and 
4 was the final formula for the principal filling 
for this bomb. 

5. 30% Gasoline-rubber gel (7% rubber) 
11% Aluminum powder 
14% Sulfur 

45% Sodium nitrate with or without 
2%% cotton or other vegetable fiber 
for strengthening. 

This mixture was investigated as a possible 
flame-thrower fuel. It showed promise except 
for the unavailability of rubber. 

Nuodex Products Co.‘‘ experimented with a 
variety of mixtures of gasoline gel, oxidizing 
agents, such as lead nitrate, barium nitrate, and 
lead oxides, and metals or other reducing 
agents, such as lead, iron, lead sulfide, and iron 
sulfide, in an attempt to find a satisfactory 
high density flame-thrower fuel. Densities in 
the range 1.3 to 1.6 were achieved. The prin¬ 
cipal requirements were high cohesiveness, re¬ 
liable burning, and stability. No mixtures of 
practical value resulted from this work. 

«...3 Hydrocarl)on-Oxidizing Agent 
Mixtures""- 

1. 58.5% Turpentine 

19.5% Furfural extract, from lube-oil re¬ 
fining 

10% Ammonium nitrate 
12% Cellucotton 

This mixture was developed for the E9 bomb 
and was highly recommended for that purpose, 
except that the final design of the E9 bomb was 
not adapted to the use of cellucotton-bodied 
fuels. 

2. 30 Polymerized divinyl acetylene 

(DVA) 

10%' Motor oil 
60% Sodium nitrate 

This mixture was developed at the University 
of Chicago for use in sabotage incendiaries. 
The test results showed that divinyl acetylene 
had no greater fire-starting capacity than other 
hydrocarbons. 



212 


FUELS FOR INCENDIARIES AND FLAME THROWERS 


* Hydrocarbon-Metal Mixtures"'^’ 

1. 58.5% Turpentine 

19.5% Furfural extract, from lube-oil re¬ 
fining 

10% Magnesium powder 

12 % Cellucotton 

This mixture was developed for the E9 bomb. 
The comparatively high burning temperatures 
of the hydrocarbons present were sufficient to 
ignite the magnesium, and it gave a very effec¬ 
tive incendiary fuel. 

2. 98% Gasoline gel (Napalm) 

2% Sodium or potassium 
Finely divided sodium or potassium was made 
by melting the metals under a high-boiling 
hydrocarbon such as xylene, and then shaking 
the molten mixture, reducing the metal to fine 
droplets. The dispersed metal was then sus¬ 
pended in gasoline and the gasoline gelled with 
Napalm. These mixtures had the interesting 
property of bursting into flame when water 
was applied to them. 


8 « SELF-IGNITING FUELS*^ 

Introduction 

Substances which ignite more or less spon¬ 
taneously upon contact with the atmosphere 
have been known and studied for a long time. 
Among those considered at one time or another 
as potentially suitable for use as primary or 
auxiliary fuels in flame throwers or incendi¬ 
aries, two groups of substances stand out: 
organometallic compounds and liquefied white 
phosphorus compositions, although a variety of 
other substances has been contemplated as 
chemical igniters for flame throwers.®*^ 

Investigations of organometallic compounds 
within NDRC were initiated in 1940 under Con¬ 
tract NDCrc-61, later changed to Contract 
OEMsr-97.®8. Ignition of flame throwers by in¬ 
troducing zinc diethyl as a secondary fuel also 
received brief study under OSRD Contract 
OEMsr-21 early in 1944. Liquefied phosphorus 
compositions were taken up by NDRC as pos¬ 
sible flame-thrower fuels in April 1944 under 
Contract OEMsr-242, and this work resulted in 


an intensive study of the preparation, proper¬ 
ties, applications, and physiological effects of 
liquefied phosphorus, as well as in design of 
instruments for its military use.®” ^'^ 


8.8.2 Organometallic Compounds 

Nitrated Lead Derivatives^^ A number of 
these compounds decompose vigorously or ex¬ 
plosively when heated, to give fine lead oxide 
smokes. The ballistic properties of these sub¬ 
stances, however, are too low to warrant their 
consideration as explosives, although some of 
them suggest approaches to possible primers. 
The toxicity of these lead and lead oxide smokes 
has received only scant investigation. 

Nitrated Arsenic Derivatives^'^ Some of these 
compounds decompose explosively when heated, 
to give fine arsenic oxide smokes; this is par¬ 
ticularly the case with nitro-aryl arsenic acids 
and their lead salts. The presence of lead gen¬ 
erally increases the explosive properties of 
nitrated arsenic acids. 

Bismuth Compoimds.^^ Organobismuth com¬ 
pounds containing two or more nitro groups in 
the molecule give off a bismuth oxide smoke 
upon ignition. However, self-igniting proper¬ 
ties are low. 

Aluminum CompoundsN^ Methylaluminum 
sesquichloride, (CH 3 ) 3 ALCl 3 , a compound read¬ 
ily prepared by direct interaction of aluminum 
and methyl chloride, appears to possess some 
interest as a flame-thrower igniter or primary 
fuel. 

Diethyl Zmc. This compound, although not as 
yet readily available, appears to possess some 
interest as a flame-thrower igniter. A dis¬ 
advantage is the high proportion of zinc diethyl 
required as a flame-thrower rod coating, espe¬ 
cially in cold weather. 

Triethyl BoronA"^ In the course of the exami¬ 
nation of a number of spontaneously inflamma¬ 
ble substances for possible use as incendiary 
agents, triethyl boron was found to possess 
certain advantages, such as moderate thermal 
stability and high stability toward water, which 
were not exhibited by any other of the possible 
liquid substances. 

The ordinary laboratory procedures for the 



SELF-IGNITING FUELS 


213 


preparation of this compound are, unfortu¬ 
nately, not satisfactory for large-scale indus¬ 
trial use. It was, therefore, the object of the 
research to develop a simple method for the 
synthesis of the compound from readily avail¬ 
able materials and in conventional equipment 
used by the chemical industries. 

In all, forty-three experiments were carried 
out, using all reasonably available starting ma¬ 
terials and a great variety of conditions. Of 
these, only eight gave any trace of the desired 
product, and only two were sufficiently con¬ 
venient and economical of material to merit 
consideration. These two methods involve the 
reaction of ethylaluminum sesquibromide (1) 
with triethyl borate and (2) with gaseous boron 
trifluoride. Of these two, the procedure em¬ 
ploying ethylaluminum sesquibromide and tri¬ 
ethyl borate appears to be most satisfactory on 
the basis of both yield and economy. No solvent 
is needed, the only starting materials being 
aluminum turnings, ethyl bromide, and triethyl 
borate. Scrap aluminum may be employed in 
place of the pure metal if the latter is not avail¬ 
able. The first of the two steps in the reaction 
may be operated as a continuous process. The 
conversion of the aluminum compound to tri¬ 
ethyl boron is quantitative, and it is conceivable 
that the aluminum residues could be returned 
to a refining plant and converted to the metal. 


8.8.3 phosplioriis-Phospliorns Sesqiiisulfide 
Eutectic (EWP) 

Liquid The phosphorus-phosphorus 

sesquisulfide eutectic consists of 55 per cent 
by weight of white phosphorus and 45 per 
cent by weight of phosphorus sesquisulfide. The 
composition by elements is 80 per cent phos¬ 
phorus and 20 per cent sulfur. The composition 
of the fuel is not critical, and a reasonable 
amount of deviation is allowable from the true 
eutectic proportions. 

The fuel, when settled free from water, is a 
clear, yellow, heavy liquid of low surface ten¬ 
sion, moderate viscosity, and oily appearance. 

The specific gravity of the phosphorus-phos¬ 
phorus sesquisulfide eutectic at 20 C is 1.840, 
as determined with a pycnometer. 


Mixtures containing 40 per cent phosphorus 
sesquisulfide and 60 per cent white phosphorus 
possess a viscosity 5 to 6 times that of water at 
temperatures from 10 to 60 C. 

The surface tension of the eutectic fuel has 
not been measured, but is believed to be much 
lower than that of water. 

The eutectic fuel freezes at approximately 
—42 C. A tendency toward supercooling has 
been noted. However, samples of fuel main¬ 
tained at —40 C for a period of several weeks, 
with periodic agitation, have remained con¬ 
sistently liquid. Samples solidified at lower tem¬ 
peratures and remelted several times continued 
to show consistent freezing between —40 C and 
-45 C. 

Upon exposure to light for several days, the 
eutectic fuel gradually deteriorates and becomes 
turbid. It is believed that the change is due to 
the conversion of white phosphorus into the 
red modification. When the liquid is stored in 
the dark, or in opaque containers, no deteriora¬ 
tion takes place. 

When the phosphorus-phosphorus sesquisul¬ 
fide eutectic is agitated with water, there is a 
tendency toward some dispersion of water in 
the eutectic, the clear fuel settling out com¬ 
pletely only after several hours. Storage of the 
eutectic under a layer of water for several 
weeks at ambient temperature indicates no 
appreciable reaction beyond the formation of 
a slight yellow scum at the interface and the 
gradual acidification of the aqueous phase. 
Tests to determine stability in contact with 
water at —40 (ice) and 55 C failed to show any 
deterioration. 

Samples of the eutectic fuel contained in light¬ 
proof vessels were placed in a freezing mixture 
at —40 C and in an oven maintained at 55 C. 
Another sample was alternately exposed to 
these temperature conditions for two-hour in¬ 
tervals, with intermediate one-hour intervals 
at room temperature. The tests, after proceed¬ 
ing for 60 days, disclosed no apparent de¬ 
terioration of the phosphorus-phosphorus 
sesquisulfide solution. 

A sample of the fuel was placed in a light¬ 
proof flask filled with COo and exposed to a 
temperature of 212 F for 10 hr a day for 30 
days. The pressure in the system as measured 





214 


FUELS FOR INCENDIARIES AND ELAME THROWERS 


by an attached mercury manometer showed no 
appreciable change. The appearance of the fuel 
was unchanged. 

Strips of different materials were immersed 
in vessels containing the eutectic fuel under 
a layer of water, and were allowed to remain 
in contact with the liquid for 24 days. Inspec¬ 
tion of the specimens showed the following 
results: 


Material 

Steel 

Lead 

Tin 

Copper 

Aluminum 

Rubber 

Neoprene 

Polystyrene 

Ethyl cellulose 


Condition after test 

Somewhat cori’oded 

Slightly tarnished 

Slightly tarnished 

Blackened 

Unaffected 

Unaffected 

Unaffected 

Unaffected 

Unaffected 


A 2-gal sample of eutectic fuel was stored 
under water in a tightly sealed steel container, 
at prevailing outdoor temperatures, from Janu¬ 
ary until June 1945. Upon opening the steel 
drum it was found that only very slight pres¬ 
sure had developed, probably largely attributa¬ 
ble to the change in ambient temperature; the 
eutectic was clear yellow in color; and when 
poured from the container, the fuel ignited 
instantaneously. 

Self-ignition of the phosphorus-phosphorus 
sesquisulfide eutectic is a function of tempera¬ 
ture and agitation of the fuel. For instantaneous 
self-ignition in a completely undisturbed state 
as, for example, when exposed to still air in a 
flat dish, the temperature of the fuel must be 
at least approximately 20 C. Any movement of 
the liquid, however, against the walls of the 
containing vessels, air currents against the 
surface of the liquid, exposure to sunlight, etc., 
tend to lower the self-ignition temperature, so 
that the exact ignition temperature in a state 
of rest is difficult to determine without elaborate 
precautions. 

As the eutectic fuel is subjected to more 
violent mechanical disturbance, its self-ignition 
temperature drops sharply. To test ignition 
quality under conditions of violent impact, 
bottles filled with eutectic fuel were cooled in a 
dry ice mixture to a temperature of —50 C, at 
which the fuel was solid. Upon being flung 
against a wall, the fuel ignited violently im¬ 


mediately upon bursting of the bottle. This 
test was repeated many times with identical 
results. 

When the eutectic fuel is ejected from an 
experimental flame thrower at temperatures 
above approximately 15 C, spontaneous ignition 
takes place at the nozzle. At lower tempera¬ 
tures, ignition is more likely to occur in flight 
or upon impact. While impact ignition is likely 
to decrease somewhat the range of the fuel, it 
is believed that, in the case of a fuel of the high 
specific gravity of the eutectic, the difference 
between ignited and unignited range would not 
be very significant. On the other hand, the de¬ 
livery of an increased amount of fuel on the 
target, without loss by combustion during flight, 
has obvious advantages. For description and 
illustrations of devices using EWP fuels see 
Sections 4.4 and 6.7. 

The phosphorus-phosphorus sesquisulfide eu¬ 
tectic burns largely to P.Os and SO,, resulting 
in the production of extraordinary quantities 
of very dense, white smoke; this smoke is very 
persistent and highly irritating. Appreciable 
amounts of sticky residue are also formed dur¬ 
ing combustion. It is believed that this residue 
consists largely of syrupy oxides of phosphorus, 
phosphoric acids (formed by hydration upon 
contact with atmospheric moisture), some ele¬ 
mentary sulfur, and minor amounts of occluded 
elementary phosphorus. This residue is highly 
hygroscopic. Combustion of the fuel always re¬ 
sults in a strong odor of phosphine in the 
vicinity; this odor tends to persist for days. 

Thickened EWP.^^ When the phosphorus- 
phosphorus sesquisulfide eutectic (EWP) de¬ 
scribed above is ejected from a nozzle and ig¬ 
nites upon ejection, the flaming liquid tends to 
spray out into the air in a bushy pattern some¬ 
what resembling that obtained when using un¬ 
thickened hydrocarbon fuels in a conventional 
portable flame thrower. Although the high spe¬ 
cific gravity of EWP and its somewhat slower 
burning rate, as compared with gasoline, permit 
it to attain an appreciably greater range than 
the latter under analogous conditions of ejec¬ 
tion, much of the thickened EWP tends to burn 
in the air, the ballistic characteristics of the 
fuel are mediocre, and not enough of it is de¬ 
posited on the ground or on a target. 



FUNDAMENTAL STUDY OF ALUMINUM SOAPS 


215 


It was therefore desirable to modify the EWP 
fuel in such a manner as to obtain it in thick¬ 
ened, preferably gel form, to make possible im¬ 
proved ballistic characteristics and increased 
range. 

To date, no completely satisfactory thickened 
EWP fuel has as yet been produced; and much 
work still remains to be done on the formula¬ 
tion, stabilization, and use of thickened EWP 
fuels, as well as on the design of appropriate 
instrumentation for their use. 

Attempts to produce an EWP gel analogous 
to Napalm-thickened gasoline have met with 
no success to date. Unlike petroleum prod¬ 
ucts, the phosphorus-phosphorus sesquisulfide 
eutectic appears incapable of forming a gel 
structure with any known agent. It is im¬ 
miscible with Napalm or any similar metal 
soaps; and while mixing with a gasoline-rubber 
cement results in a fairly stable mixture, the 
latter is definitely a mechanical suspension, 
which remains stable merely as a result of the 
high viscosity of the medium. 

A stable mixture has been prepared by in¬ 
corporating in the liquid EWP 0.75 to 1.00 lb 
carbon black per gal EWP, The product is a 
short, thick paste, which has been kept stable 
under ambient conditions for as long as two 
months, and which has shown good ignition, 
range, and burning characteristics. However, 
not much is known about the stability and 
viscosity characteristics of this mixture under 
widely different temperature conditions. 

A modification of the above formulation con¬ 
tains 1 gal of liquid EWP, 2 lb carbon black, 
and 1 gal of a varnish consisting of 200 lb 
rosin, 15 lb fuel oil No. 2, and 1 qt gasoline. 
This mixture has been found to result in a 
stringier fuel than the straight EWP-carbon 
black formulation, but it suffers the disad¬ 
vantage of retarded ignition. 

In addition to carbon black, the following 
substances have also been used as thickeners 
for EWP: baking soda, borax, boric acid, 
powdered lime rosin, and fuller’s earth. As the 
addition of carbon black considerably increased 
the range of EWP, and as the effect of this 
added agent appeared to be caused not so much 
by the mechanical raising of the viscosity as 
by delaying the burning rate, baking soda was 


incorporated in EWP, with the idea of pro¬ 
ducing an envelope of carbon dioxide to offset 
too rapid burning. Borax and boric acid were 
added to form crusts for the protection of the 
fuel in transit against excessively rapid burn¬ 
ing. These agents gave increased range, but 
were most helpful in emulsions. 

In an attempt to retard the burning speed 
of emulsions, carbon tetrachloride and water 
were tried, both without success. The carbon 
tetrachloride reacted in the flame, merely cut¬ 
ting down on total heat, and the water, prob¬ 
ably through rapid volatilization, actually in¬ 
creased the burning rate. 

Up to this point in the work the most success¬ 
ful mixture found was an emulsion of about 
equal parts by weight of rubber cement and 
EWP, preferably with the addition of bicar¬ 
bonate of soda. With this mixture, a range of 
80 yd could be obtained with good delivery of 
fuel on the far end of the range, which was 
always well covered with lumps of the burning 
mixtures. Rubber cement also has the ad¬ 
vantage of being inert to acid and water. While 
natural rubber was used, oil-soluble synthetics 
might be of value here. 


8 9 FUNDAMENTAL STUDY OF ALUMINUM 
SOAPS29- 84 

In the early development work on Napalm 
and related thickening agents there were no 
reliable basic data on the chemistry of alu¬ 
minum soaps. Even their existence as definite 
compounds was problematical. Much more 
knowledge of pure aluminum soaps was needed 
before applications could be made to the com¬ 
plex mixtures forming Napalm soaps and 
Napalm-thickened fuels. 

The methods used in this study cannot be 
summarized here because of their highly tech¬ 
nical and involved character, and must be found 
in the pertinent references.89- 34 Only the most 
important conclusions reached by these methods 
can be summarized here. 

The most important aluminum soaps are di¬ 
soaps, corresponding to the formula Al(OH)R. 
where R is an acid radical. They form the bulk 
of Napalm soaps. 



216 


FUELS FOR INCENDIARIES AND FLAME THROWERS 


The properties of these soaps depend, of 
course, on the nature of the acid involved, its 
molecular weight, whether fatty or naphthenic, 
etc. In addition, a surprisingly large influence 
upon both its chemical and physical properties 
is exercised by the physical state of the soap, 
the degree of crystallinity of its structure. 

For instance, aluminum dilaurate, an im¬ 
portant constituent of Napalm, has been pre¬ 
pared in a high degree of purity in forms hav¬ 
ing the same composition but ranging from a 
highly crystalline and brittle, to an almost 
amorphous and fluffy solid. The former is inert 
to hydrocarbons at room temperature; the lat¬ 
ter dissolves readily. 

In contradistinction to di-soaps Al(OH)R 2 , 
neither the mono-soaps AlOR nor the tri-soaps 
AIR 3 play an important role in Napalms. The 
former exist and can be prepared under special 
conditions, and the latter have probably never 
yet been prepared. 

Fatty acids, although not combining with 
di-soap to form tri-soap, are readily sorbed 
by them and may be held quite tenaciously. 
Thus the small proportion of acids present in 
Napalm in excess of that forming di-soaps is 
neither combined nor truly free. It is held 
sorbed by surface forces. 

In the presence of gasoline and other hydro¬ 
carbons aluminum soaps may show the full 
range of behavior from complete inertness, 
through swelling and thickening, to complete 
solution. What occurs in each particular case 
depends on the physical state of the soap, as 
mentioned above, as well as the nature of the 
acid forming the soap and that of the hydro¬ 
carbon, the temperature, and the presence of 
additives. It appears that any typical behavior 
may be produced, within reason, by varying any 
of these factors. 

At low temperature a distinct gel phase is 
formed in general, in which the soap imbibes a 
certain amount of hydrocarbon, sometimes 50 
volumes or more, but its particles remain sep¬ 
arate and an excess of hydrocarbon will not 
be taken up. This is an opalescent, noncoherent, 
nonstringy, “applesaucy,” or even syneretic, 
mass such as formed by Napalm soap at low 
temperatures and with high aniline-point gaso¬ 
lines. 


The jelly-sol phase is formed at higher tem¬ 
peratures. Here the discrete particles have 
disappeared and a coherent, elastic, rigid jelly 
or a thin, easily flowing sol exists, such as 
formed by Napalm under ordinary conditions. 
Excess solvent is taken up spontaneously, and 
in the case of pure soap a clear system is 
formed. 

The transition from jelly to sol and vice versa 
is gradual, depending on temperature and con¬ 
centration without any definite boundary be¬ 
tween them. 

The transition from gel to jelly or sol, on the 
other hand, is sharp and may be rather easily 
observed. 

Each of these forms is truly stable over cer¬ 
tain ranges of conditions, but the jelly in par¬ 
ticular may exist, without being stable, over 
a much wider range. Changes in viscosity cor¬ 
responding to changes from jelly to sol may be 
very slow but start readily. This is the well- 
known aging of Napalm fuels. The onset of a 
change from a jelly to gel, on the other hand, 
does not occur readily in the absence of ade¬ 
quate seeding. The loss of coherence and pos¬ 
sible syneresis may therefore be suspended for 
long periods of time running into years, even 
under conditions where it is finally bound to 
occur. 

The transition temperature between gel and 
jelly depends on many factors, but for any given 
system the jelly cannot be indefinitely stable 
below this temperature. This fact suggests spe¬ 
cial problems connected with long-range stor¬ 
age of thickened fuels, particularly at low or 
cycling temperatures. 

The properties of a mixture of aluminum 
soap with hydrocarbons, such as Napalm and 
gasoline, can be deeply influenced by the pres¬ 
ence of many other substances, sometimes even 
of small amounts. The additive may accelerate 
or retard the interaction of the two, increase or 
decrease the final viscosity, change it toward 
dilatancy or towards plasticity (thixotropy). 
Each of the pairs of influences is independ¬ 
ent and may be in either direction. The effect 
of a given additive may depend greatly on tem¬ 
perature, concentration, and even on the par¬ 
ticular sample of Napalm studied. 

Various samples of Napalm, although satis- 




FUNDAMENTAL STUDIES ON RHEOLOGICAL PROPERTIES 


217 


fying the requirements of the specification, 
differ when tested by other methods or under 
other conditions, to the point where the name 
Napalm appears almost to be their only com¬ 
mon characteristic. These differences between 
Napalms manufactured under slightly varying 
conditions are not surprising. As mentioned 
above, both the physical state and small amounts 
of extraneous substances greatly influence the 
properties of all aluminum soaps. This em¬ 
phasizes the need for more thorough character¬ 
ization of Napalm from the point of view of 
physical state and impurities, and the study of 
the influence of manufacturing methods upon 
both. 

Only a beginning could be made in the study 
of physical states of Napalms by various ex¬ 
traction and X-ray methods. Considerable prog¬ 
ress was made in identifying in Napalm small 
amounts of several constituents absent from 
pure soap. Some of these were quite unexpected. 
Napalm may contain small amounts of inor¬ 
ganic substances, largely basic aluminum salts; 
hydrocarbon soluble sodium soaps; nitrogen 
(may be from proteins) ; partially volatile un¬ 


combined acids and unsaponifiables, and, of 
course, water. The bulk of Napalms, as already 
stated, consists of di-soaps. 


» FUNDAMENTAL STUDIES ON 

RHEOLOGICAL PROPERTIES" 

The superior performance of thickened or 
gelled hydrocarbon fuels as contrasted to un¬ 
thickened fuels was early recognized to be due, 
in large part, to their unusual flow character¬ 
istics. 

Gels are dispersions which, when slightly 
stressed, exhibit elastic deformation, or strain, 
followed by a return to the original position 
upon removal of the stress. Gels exhibiting only 
elastic deformation until a definite shearing 
stress is exceeded may be thought to possess 
an elastic limit or “yield value,” below which 
no real or permanent flow occurs. Napalm gels 
containing milled paper pulp and the IM-II gel 
behave in this manner (see Table 3). 

a See references 14, 16, 18, 19, 21, 22, 25-28, 30, 31, 33, 
36, 38, 40, 42, 44, 46, 48, 49, 52, 53, 91-102. 


Table 3. Elastic properties of incendiary gels. 



Shear! 

Relaxation! 

Extensi¬ 

Healing 

Healing 



modulus 

time 

bility 

time 

rate 


Incendiary fuel* 

dynes/cnR 

sec 

in. 

sec 

constant 

Notes 

4% Napalm+ 10% MPP 

21,000 

Does not relax 




Yield value 

6% Napalm 

300-550 

17-20 


10 

0.20 


8% Napalm 

700-1450 




0.12 


9% Napalm 

1400-2800 

10-16 

'll' 

35 

0.10) 

Equal 

range 

10% Napalm 

1700 


3 


....) 

8% Napalni+0.25% PPR 

2800 


1 

4 


,...J 

8% Napalm+ 2.0% PPR 

4100 


0 



25% less range 







Yield value 

12% Napalm 

3400-4250 

6-18 


90 

0.06 


13.5% Napalm 

2500-5300 

6-30 



0.04 


IM-II 

2600 

Does not relax 


8 hr 


Yield value 

2% IM+0.3% IP 

24-97 

5-10 




Work harden 

5% IM+0.3% IP 

1020-1250 

40 




Work harden 

3% IM+0.1% IP 

3 



75 


Work harden 

5% IM+0.1% IP 

185-700 

16-30 


130 


Work harden 

Ml Gel 

1100-2700 







*M1 Gel = Gel described in CWS Spec. 196-131-102. 

PPR = Poly pale resin (Hercules). 

MPP = Milled paper pulp. 

IM = Isobutyl methacrylate. 

IP = Interpolymer. 

tMeasured in Clark-Hodsman viscosimeter, or Jeweler’s lathe viscosimeter, or in the Sandvik-Goldberg resonance elastometer. For description of the 
latter, see Appendix II, Rheological Properties of Thickened Fluids, Eastman Kodak Co., May 7, 1943.- 
tTime for stress needed to maintain constant strain to fall to 1/e its initial value. 


jCONFTDEKT iar 






























218 


FUELS FOR INCENDIARIES AND FLAME THROWERS 


Other incendiary fuels possess such low 
strength that they are unable to support them¬ 
selves when deprived of the support offered by 
the walls of their container and possess little, 
if any, yield value. These gels, after being 
slightly stressed, momentarily will return to 
their original position upon removal of the 
stress, but upon prolonged application of stress 
fail to do so, the gel accommodating itself to 
the stress, or relaxing by a slow flow or creep 
process. Such a process is referred to as relaxa¬ 
tion, a gradually smaller force or stress, ulti¬ 
mately approaching zero, being required to 
maintain the material in the stretched or 
strained condition. The relaxation experi¬ 
mentally observed in such incendiary fuels ac¬ 
counts for the impossibility of measuring yield 
value in long-time static tests. Relaxation is a 
manifestation of imperfect elastic nature and 
not true flow in the ordinary sense of the word. 
It may be considered as microflow in contrast 
to true, real or macroflow. 

With gradually increasing stress a point is 
ultimately reached where gel flow proceeds no 
longer by the relatively slow creep or relaxation 
process, but by a process of actual shear or slid¬ 


ing of one complete layer of gel along its neigh¬ 
boring layer. This point may be called the shear 
initiation point, and the shearing stress re¬ 
quired, the shear initiation stress. In actual 
measurement, such flow transition may appear 
gradual rather than abrupt, on account of a 
changing amount of relaxation. 

Beyond the shear initiation point, gels flow 
somewhat as ordinary liquids do. The resistance 
of an ordinary (or Newtonian) liquid to flow 
is called its viscosity. The coefficient of viscosity 
(q) is defined as the shearing stress (F) di¬ 
vided by the rate of shear or shear gradient 
(S), and at constant temperature its value is 
independent of shear rate (q = F/S ). 

Incendiary gels are, however, non-Newtonian 
materials, the viscosity of which varies with the 
shearing stress to which they are subjected. 
The viscosimeters which have been employed 
to measure viscosity of gels are listed in Table 
4 in order of shear range. The first four are 
rotational instruments which measure the vis¬ 
cosity of a confined sample. In the last four 
instruments a continuously fresh supply of ma¬ 
terial is forced into the capillary, pipe, or 
perforated disk. The latter do not attain steady- 


Table 4. Viscosimeters employed for incendiary gels. 




-Shear range 

Steady 

Material 

Uniform 

Name 

Type 

sec~i 

state 

renewed 

stress 

Clark-Hodsman 

Concentric cylinder, hand-operated. 7q=2.d cm 
/T. = 2.58cm. 

0 . 01 - 1.0 

No 

No 

Yes 

Stormer (modified) 

Paddle rotated in cup by falling weights. 

0.0.5-1.0 

Yes 

No 

No 

MacMicliael 

Concentric cylinder in motor-driven cup. Inner cyl¬ 
inder suspended from torsion wire. 

3-100 

No 

No 

No 

Jeweler's lathe 

Concentric cylinder in motor-driven cup 72i=2.v30 
772 = 2.58. Inner cylinder suspended from drill rod. 
Mirror used as ojitical lever. 

10-300 

No 

No 

Yes 

High-pressure 

capillary 

Glass capillary tubes 2V' long, r = 0.0097 & 0.021 cm. 
Nitrogen gas pressure to 2,000 psi as force. 

1000 - 100,000 

No 

Yes 

No 

Grease gun 

Hand-driven screw feed. Pressure drop along length of 
i" pipe measured by gauge. 

0 . 2-120 

Yes 

Yes 

No 

I’ipc flow 

Use of variable speed positive-displacement pump to 
measure pressure loss over length of -g", 4 ", 1 U > 

\h" std. pipe. 

0.3-11,000 

Yes 

Yes 

No 

Gardner 

mobilomcter 

Perforated disk pushed into sample in vertical cylinder. 


No 

Yes 

No 


















FUNDAMENTAL STUDIES ON KHEOLOGICAL PROPERTIES 


219 


state flow conditions, except in case of grease- 
gun and pipe-flow measurements where pressure 
loss is measured over a length at some distance 
from the point of entry. The Clark-Hodsman 
and Jeweler’s lathe instruments confine the 
sample to a narrow annular ring at some dis¬ 
tance from the axis so that the entire sample 
is subjected to nearly the same shearing stress. 
All other instruments impose a wide range of 
stresses on different parts of the sample. Thus 
inflow of gel through a capillary tube or pipe 
to the central parts may be stressed only elasti¬ 
cally and the resulting flow, if any, will be of 
the creep or relaxation type, while the outer 
parts may possess actual shear between ad¬ 
jacent layers. Layers being sheared are under 
a wide range of stresses, with consequent varia- 



Figure 2. Various types of flow. 

tion in viscosity from one layer to the next. 
Under these circumstances, one measures only 
an apparent viscosity, that is, the sample ap- 




































































































































































































220 


FUELS FOR INCENDIARIES AND FLAME THROWERS 


pears to have the same resistance to flow as 
a normal liquid of the stated viscosity. The 
shearing stress due to the pressure imposed is 
zero at the axis and PR/2L at the periphery. 

For a normal liquid, the rate of shear is zero 
at the axis and AV/R at the periphery, velocity 
distribution being as shown in Figure 2A. 
Viscosity (q) thus becomes 

^F^PR'IL^ PR- 
^ S 4V/R SVL' 

For a non-Newtonian material the shearing 
stress at the tube wall, or elsewhere, can still 


be computed accurately, but the rate of shear 
at any layer is uncertain. This is caused by the 
presence of a central region surrounding the 
axis in which shearing stress is too low to 
cause shear or flow to occur. A gel which pos¬ 
sesses a definite yield value will not shear at all 
in those regions where shearing stress (F) is 
less than the yield value (/). Shear will com¬ 
mence at that radius where shearing stress 
{PR/2L) just equals yield value (/), and the 
velocity distribution across such a stream of 
gel will be as in Figure 2B. Such a gel is said 


Table 5. Steady-state flow of gels in pipe. 



6 % N a p a 1 

m 



7% Napalm4-2.5% Xylenols 



App. rate 





App. rate 



Pressure 

of shear 

Apparent 

Std. 


Pressure 

of shear 

Apparent 

Flow rate 

loss/ft 

at wall 

viscosity 

pipe 

Flow rate 

loss/ft 

at wall 

viscosity 

gal/min 

lb/in.2 

sec^i 

poises 

size 

gal/min 

lb/in.2 

sec~^ 

poises 

0.033 

0.51 

0.31 

3800 

IK" 

0.866 

0.21 

8.11 

60 

0.067 

0.51 

0.63 

1870 


3.58 

0.28 

33.7 

19.2 

0.267 

0.50 

2.50 ! 

462 


8.33 

0.33 

78.0 

9.8 

2.33 

0.51 

21.8 1 

54 


14.00 

0.35 

131 

6.18 

8.75 

0.58 

82 

16.4 


21.70 

0.37 

203 

4.22 

15.00 

0.54 

140 

8.98 


29.20 

0.40 

274 

3.38 

16.00 

0.63 

150 1 

9.72 






21.80 

0.64 

204 

7.36 






31.30 

0.60 

293 

4.74 






1.58 

1.10 

111 

11.72 


1.80 

0.65 

126 

6.12 

7.58 

1.36 

530 

1 3.04 


5.36 

0.82 

375 

2.58 

15.25 

1.63 

1070 

1 1.80 


11.20 

0.98 

784 

1.48 

22.00 

1.75 

1540 

i 1.34 


20.00 

1.16 

1400 

0.98 






26.3 

1.30 

1840 

0.84 






32.3 

1.41 

2260 

0.74 

0.0165 

2.60 

33.2 

30.4 


0.01 

1.50 

20.1 

29.00 

0.416 

3.87 

837 

1.74 


0.43 

2.82 

864 

1.31 

1.21 

5.04 

2435 

0.80 


0.56 

3.87 

1125 

1.33 

1.83 

5.60 

1 3680 

1 0.59 







Results below from grease gun viscosimeter 


0.00012 

0.675 

0.242 

1085 


0.0003 

0.49 

0.605 

314 


0.88 

0.400 

854 



0.65 

1.21 

206 


1.06 

0.605 

684 



0.83 

2.42 

132 


1.41 

1.21 

453 



1.08 

4.84 

86.8 


1.76 

2.42 

282 



1.26 

7.26 

67.5 


1.94 

3.63 

208 



1.55 

14.50 

41.4 


2.06 

4.84 

166 



1.78 

29.00 

23.8 


2.19 

7.26 

117 



2.06 

58.00 

13.8 


2.58 

14.50 

69 


0.060 

2.32 

121.00 

7.44 

0.0144 

3.00 

29.00 

40.4 







1.86 

2.42 

299 







2.13 

4.84 

171 







2.31 

7.26 

123 







2.83 

14.50 

75.5 






0.0144 

3.85 

29.00 

51.5 


































FUNDAMENTAL STUDIES ON RHEOLOGICAL PROPERTIES 


221 



Figure 4. Factors for computing velocity of plastic flow in pipes. 


to be plastic. If the gel possesses no measurable 
static yield value, but flows by a creep or re¬ 
laxation process until a certain shear initiation 
stress is exceeded, then its flow in capillaries 
or pipes will resemble Figure 2C with a central 
region in which stress (F = PR/2L) is below 
the shear initiation stress and flow by the rela¬ 
tively slow creep process only occurs, sur¬ 
rounded by a region in which actual shear or 
macroflow takes place. Such a gel is called a 
pseudoplastic gel. Rates of shear at the tube 
wall are much greater for plastic and pseudo¬ 
plastic materials, Figure 2B and C, than for a 
normal liquid (2A) at the same total flow rate. 
Experimentally, it is practically impossible to 
isolate a small sample of gel and test it under 
such conditions that the entire sample is sub¬ 
jected to the same shearing stress. The Clark- 
Hodsman and Jeweler’s lathe instruments 
approximate this condition, both shearing a nar¬ 
row layer between 1.15 and 1.29 cm radii, all 


the sample being stressed between 89 and 100 
per cent of the stress at surface of the inner 
cylinder. This is equivalent to isolating the 
20 per cent of material flowing adjacent to the 
wall of a tube or pipe. Unfortunately, the Clark- 
Hodsman instrument usually was not operated 
under conditions assuring steady-state flow. 
Consequently, apparent viscosities measured by 
the Jeweler’s lathe instrument more closely 
approach the true viscosity of the gel than the 
measurements made with other instruments. 
The five viscosimeters available for the early 
work covered various ranges of shear rate, each 
having an approximately tenfold variation in 
range. This resulted in discontinuities and un¬ 
certainties in the resultant flow curves. 

In spite of these uncertainties concerning 
viscosity measurements on gels, it is possible to 
show conclusively (Figure 3) that satisfactory 
incendiary gels possess very high viscosities 
(1,000 to 100,000 poises) at low rates of shear 























































222 


FUELS FOR INCENDIARIES AND FLAME THROWERS 


which gradually decrease as the rate of shear is 
increased until, at the highest shear rates at¬ 
tainable in the high-pressure capillary (ap¬ 
proximately 100,000 sec^^), the viscosities are of 
the order of 0.1 to 3 poises. According to this 
picture, flow of these gels in pipes should re¬ 
quire considerable applied pressure at low flow 
rates, but very little additional pressure for 
much higher flow rates. That this is so is shown 
in Table 5, where data for flow of regular and 
peptized Napalm gels in pipes of three different 
sizes are given. A thousandfold increase of flow 


rate of shear varies from zero at the tube axis 
to some value higher than the plotted point at 
the wall, and viscosity varies from some enor¬ 
mously high value, approaching infinity, in the 
central portion of the tube to a value lower 
than the plotted point at the tube wall. When 
very high rates of shear are produced at the 
tube wall, the viscosity approaches a minimum 
value somewhat higher than the constant vis¬ 
cosity of the dispersion medium, usually gaso¬ 
line. The equations given below have been de- 



2c 

rate of the 6 per cent gel in the It-i-in. pipe 
required only a 25 per cent increase of pressure. 
Such pipe-flow data actually constitute visco¬ 
metric data covering a much wider range of 
shear rates than is possible with any single one 
of the instruments previously used (see Fig¬ 
ure 3). These data are secured under steady- 
state flow conditions, and are free from the 
uncertain inlet loss and kinetic energy correc¬ 
tions associated with the use of ordinary capil¬ 
lary viscosimeters for gel measurements. Any 
single point of Figure 3 represents a composite 
or average for the stream as a whole. Actual 


Equations for Plastic Flow in Round Pipes 

/= yield value of gel in dynes/cm^ 

Mco = minimum gel viscosity at infinite shear rate, 
a = radius of tube or pipe. 

c = ratio of central unsheared plug radius to 
tube radius. 

.T = ratio of any layer’s radius to tube radius 
x = r fa. 

Equation 1. \fiscosity at radius .v 


M = ■ 


v=l- 

.r 


Equation 2. Wlocity of central plug (maximum 
velocity) 




2c 


U = 


afn 


n = 


1 — 2c+2c.'v: —.Y- 


Moo 2c 

4. Average velocity in the tube 
U-4C+3 


i/ 

Mco 


12c 


Equation 3. \’elocity at radius .y 
E quation 

Equation 5. Total volume rate of flow 

Q_Tra^fm 

Mco 

Equation 6. Apparent rate of shear at tube wall 

Moo 

Equation 7. Shearing stress at tube wall 
Equation 


Fu,= - 

c 


8. Apparent viscosity for entire cross 
section of gel 

4cm 

Equation 9. Pressure drop along pipe 
AL ac 


rived for computing the flow of plastic gels in 
pipes based upon a knowledge of the yield value 
































































































FUNDAMENTAL STUDIES ON RHEOLOGICAL PROPERTIES 


223 


(/) of the gel, and this limiting viscosity ^loo 
approached at infinite shear rate.'^ 

The quantities n, m, iv, and y are dimension¬ 
less quantities dependent only on the geometry 
of the circular path of flow, and are entirely 
accurate for the flow of any real plastic in a 
circular pipe. Values of m and w are given in 
Figure 4, values of n in Figure 5, and values of 
y in Figure 6. Figure 5 actually shows relative 
velocity variation along the tube radius for a 



Figure 6. Values of y — 1 — c/x. 

range of c values or central plug ratios. The y 
values given in Figure 6 allow computation of 
viscosity of the gel as it varies with radial dis¬ 
tance from the tube axis. The quantities / and 
/Uoo are characteristics of the plastic gel; their 
measurement is at present quite difficult. 

These equations apply to plastic flow only; no 
satisfactory adaptation or correction to make 
them applicable to pseudoplastic flow has as yet 
been evolved. 

The extent to which a 6 per cent Napalm gel 
agrees with these flow equations is shown in 
Figure 3, where the plotted points represent 

■3 A more empirical but more readily used treatment of 
pressure drop in piping carrying Napalm gels appears 
in Chapter 7, Section 7.4. 


actual data secured in the order shown in 
Table 3, and the solid curve is a plot of apparent 
viscosity from equation (8) against apparent 
shear rate from equation (6) (see above) for 
various assumed values of c which are shown 
alongside the curve. The curve is based upon 
values of ./’= 1,200 dyncs/cm- and goo =0.18 poise 
for the gel. Agreement of the flow data secured 
in the pump tests with the line representing 
the equation is excellent. The grease gun vis¬ 
cometric data secured later indicated the gel to 
be more mobile at the lower rates of shear; 
however, if we think in terms of a shear 
initiation stress, rather than yield value, of 1,200 
dynes/cm- which must be exceeded before real 
flow or shear occurs, then even these data begin 
to conform to the curve, when 96 per cent of 
the tube is occupied by the central plug. At 
c = 0.98, creep flow within the plug appears 
to amount to 50 per cent of the shear flow in the 
outer 2 per cent. When c = 0.99, creep flow in 
the central plug equals shear flow in the outer 1 
per cent. One might say that this gel appeared 
plastic in the first tests in the ll^-in. pipe and 
pseudoplastic in the later grease gun tests in 
1^,-in. pipe. It is not known whether a yield value 
and, hence plastic nature of the gel, is actually 
easier to demonstrate in a larger pipe, or 
whether the change noted is entirely an aging 
effect. It is known that Napalm gels are more 
plastic or short when first prepared, becoming 
pseudoplastic and stringy upon aging. Pseudo- 



Figure 7. Variation of torque on torsion wire 
with time: (1) ordinary viscous liquid, (2) 
Napalm incendiary gel, (3) incendiary gels IM- 
Type II, (4) incendiary gels IM-Type I. 

plasticity can also be induced by peptizing 
Napalm gels with various organic acids, alco¬ 
hols, and water. The effect of such peptization 
is shown in Figure 3 for a 7 per cent Napalm, 
2.5 per cent xylenol gel. The viscosity at low 
rates of shear is considerably reduced by the 
use of these peptizers. 
































































































































224 


FUELS FOR INCENDIARIES AND FLAME THROWERS 


In dealing with viscosity of gels, the steady 
state of equilibrium flow conditions has been 
stressed. The unsteady flow of gels or time 
effects in gel behavior are also of interest and 
may be of great importance in the flame 
thrower. We have already considered relaxa¬ 
tion, a time effect in connection with elastic 
deformation. When stresses above the shear 
initiation stress are applied to a gel, flow does 
not immediately commence against a constant 
viscosity as in the case of ordinary liquids. 
Upon starting the Jeweler’s lathe viscosimeter 
instantaneously, the force upon the torsion wire 
varies with time and the type of gel, as shown in 
Figure 7. The ordinary viscous liquid (1) de¬ 
velops a constant torque almost immediately, 
the rate of the initial steep climb being deter¬ 
mined by the speed of rotation and the stiffness 
of the torsion rod, in other words, the response 
of the system. Napalm gels (2) produce a trace 
which usually shows a slight rapid rise at the 
start similar to the normal liquid. Then the 
force gradually climbs. This may be interpreted 
as an elastic stretching of the gel which may be 
accompanied by relaxation, although the time 
available for relaxation to occur is limited to 
from 0.05 to 1 sec depending upon the speed of 
rotation. The slope of the climbing trace is 
really a measure of the elasticity or shear modu¬ 
lus of the gel, the fact that a curving line results 
indicating deviation from Hooke’s law. A steep 
slope indicates high shear modulus or a short 
gel, while a gradual slope indicates low shear 
modulus and a stringy gel. Both slope and shear 
modulus increase with increasing soap concen¬ 
tration in the gel. The faster the rotation the 
sooner peak or maximum force occurs, but for a 
single gel the peak always occurs after approxi¬ 
mately the same number of rotations. For a 
typical 9 per cent Napalm gel this may be at 
one-third of a revolution, at which point the gel 
originally lying along a radius between the 
cylinders (0.14 in.) may be thought of as 
stretched over a curving arc of about 1-in. 
length; hence it has suffered a sevenfold stretch 
before real shear has occurred. 

Slower speeds of rotation cause the maximum 
force at the hump to be less, an indication that 
relaxation or creep during the elastic stretch 
has, because of the longer time, played a more 


important role. Following the maximum, there 
is a gradual decrease until a constant force or 
torque is measured at V 2 to 2 sec following the 
start of rotation. The Jeweler’s lathe viscosity 
data of Figure 3 are based upon this part of the 
trace. This final force increases only slightly 
with great increase of rotational speed, produc¬ 
ing lines on Figure 3 which approach the limit¬ 
ing slope of 45 degrees. Another point of 
interest in these traces is the excess of area 
abed over aecd, which may be thought of as the 
additional work that must be done to the gel to 
start it flowing above that needed for a normal 
liquid of the same final viscosity. This additional 
work is greater the faster the rotation, again 
indicating less relaxation to be possible under 
such conditions. 

When such Jeweler’s lathe experiments are 
repeated upon the same gel after increasing 
time intervals, it is found that the maximum 
force developed is less than the original value, 
until a certain time has elapsed which may be 
referred to as the healing time of the gel (see 
Table 3). A 9 per cent Napalm gel shows a heal¬ 
ing time of approximately 10 sec after being 
sheared at a rate of 211 reciprocal sec. The 
bulk of healing may be completed in half of this 
time. This means that such a gel possesses the 
property of thixotropy, that is, a time lag in 
regain of initial strength following the cessa¬ 
tion of the shearing action. 

In Figure 7 curves (3) and (4) illustrate 
traces made by incendiary gels IM-Type II and 
incendiary gels IM-Type I respectively. Most of 
the useful incendiary gels investigated are, to 
some degree, thixotropic. A healing rate con¬ 
stant (similar to a first-order chemical reac¬ 
tion) better characterizes the healing process 
than the rather uncertain use of the term heal¬ 
ing time. Healing rate increases rapidly with 
increase of temperature. From the temperature 
dependence of this rate constant, the activation 
energy associated with this healing process was 
found to be 9 ± 1 kcal. This suggests that the 
linking may occur by means of hydrogen bonds. 

Incendiary gels are imperfect elastic solids 
which suffer relaxation when stressed below 
the shear initiation stress. When stressed more 
than this, they become liquefied with an appar¬ 
ent viscosity which decreases with increasing 





FUNDAMENTAL STUDIES ON RHEOLOGICAL PROPERTIES 


225 


severity of stressing, finally approaching a 
minimum limiting viscosity somewhat higher 
than that of the dispersing liquid or fuel. In¬ 
cendiary gels are thixotropic, since upon cessa¬ 
tion of stressing, time is required before they 
regain their initial elastic condition. To com¬ 
pletely describe such gels it would be necessary 
to secure the following data. 

Modulus of rigidity 
Relaxation time 
Extensibility 
Apparent viscosity 

Variation with shear rate 
Shear initiation stress 
Ultimate minimum viscosity 
Thixotropy 
Healing time 
Healing rate constant 

All the above quantities have been investigated 
on various gels at various times. To attempt to 
measure all these quantities in a routine testing 
of incendiary fuels would be unwise and time 
consuming. The one property that appeared to 
be of greatest importance in incendiary fuels 
was the extreme variation of apparent viscosity 
with shear rate. 

The Gardner mobilometer was finally chosen 
to serve as a routine testing instrument to de¬ 
termine gel quality. As used, it provides a meas¬ 
ure of gel viscosity reported as grams weight 
necessary to cause a rate of shear corresponding 
to 10 cm disk travel in 100 sec. In arriving at 
this point, several weights are employed and a 
plot of weight versus time obtained. In addi¬ 
tion to the 100-sec Gardner consistency,'^ the 
slope of such a plot furnishes a rough measure 
of the degree of pseudoplasticity (relaxation or 
stringiness) of the gel. Napalm supplied by dif¬ 
ferent sources varies only to a limited degree 
in this property. 

When ordinary liquids of low viscosity issue 
at high velocity from small nozzles, they tend to 
atomize immediately into very fine droplets. 
Liquids of moderate viscosity produce jets 
which, at some distance from the nozzle, break 
up into somewhat larger droplets. Very viscous 
liquids emerge as a smooth stream or rod that 

c The term commonly used in referring to these values, 
since the shear rate cannot be precisely determined. 


does not break up during the trajectory, which 
is, however, of limited length due to the high 
viscosity imposing a low initial velocity at the 
pressures available. Jet breakup is caused by 
surface tension of the liquid, frictional drag 
due to the surrounding air and to some extent 
aided by turbulent conditions in low viscosity 
liquids as they issue from nozzles. A very vis¬ 
cous liquid is able to resist the forces tending to 
cause jet breakup but, on account of the viscous 
parabolic velocity distribution, requires nearly 
twice the energy or pressure for a given aver¬ 
age jet velocity that a more limpid liquid in 
turbulent flow does. It is also subject to much 
higher pressure losses in pipe and nozzle. 

To secure maximum jet velocity, jet cohesion, 
and range, a type of liquid is required which has 
a sufficiently low apparent viscosity at high 
rates of shear to flow readily through pipes and 
nozzles, and a sufficiently high velocity, at the 
low rates of shear induced by friction with the 
air, after leaving the nozzle to cohere well in 
flight. The speed of the change from liquid 
condition adjacent to the nozzle wall to viscous 
condition in the emerging jet, apparently plays 
a significant role. Napalm gels which show 
much faster healing than, for example, the 
IM-II gel, have found more favor as a flame¬ 
thrower fuel. The IM-II and the Edgewood Ml 
gel have, on the other hand, proved satisfactory 
for incendiary bomb use where fast healing is 
not of such great importance. 

Another factor of great importance is the ex¬ 
tensibility, or stringiness, of the gel which has 
been experimentally observed by measuring the 
length to which a given gel can be stretched or 
extended at a fixed constant rate before rupture 
occurs. Some data of this nature are included 
in Table 3, Napalm gels can be made short 
(lack of stringiness) by addition of poly pale 
resin or milled wood pulp. These very short 
gels are quite plastic, showing a definite yield 
value. The IM-II gel also possesses a definite 
yield value. Such short gels do not behave well 
in flame throwers. The jet of gel issuing from 
the flame-thrower nozzles consists of an elastic 
core surrounded by layers of gel which have 
been sheared. This elastic core is stretched and 
compressed in the nozzle. If this strain is too 
great, as in the short gels, the rod of fuel issuing 


j bNFID~E NTia]9 







226 


FUELS FOR INCENDIARIES AND FLAIME THROWERS 


from the nozzle pulls apart into separate small 
chunks which offer so great a surface that drag, 
due to air resistance, reduces the range. A less 
plastic or pseudoplastic gel which is capable of 
relaxing or creeping in the central elastic core 
accommodates itself to the elastic strains set up 
in going through the nozzle so that it holds to¬ 
gether as a continuous rod upon issuing from 


the nozzle, contracting only sufficiently to offset 
the decreasing jet velocity. If the stringiness is 
too great so that practically no elastic recovery 
occurs as the jet or rod slows down, then loop¬ 
ing into folds may occur. However, there is no 
definite evidence that excess stringiness, relaxa¬ 
tion, or pseudoplasticity exerts a harmful influ¬ 
ence on the range. 



GLOSSARY 


EWP. Phosphorus-phosphorus sesquisulfide eutectic. 
FRAS. Aluminum stearate-thickened fuel. 

IM. Gasoline gel of the isobutyl methacrylate type. 
NP. Gasoline gel of Napalm type. 


PT. Pyrotechnic mix. 

SCFH. Standard cubic foot per hour. 
SDO. Synthetic drying oil. 

WP. White phosphorus. 


227 







I 


i 


1 



4 











'C. 








:* • 


^iAfTKaonv.oo 


k 


• % 





.1 


' '4VAii 


H-t. _ 


S 





I 


f . 

“I 



f 



BIBLIOGRAPHY 


Numbers such as Div. 11-301.4-Ml indicate that the document listed has been microfilmed and that its 
title appears in the microfilm index printed in a separate volume. For access to the index volume and to the 
microfilm, consult the Ai-my or Navy agency listed on the reverse of the half-title page. 

CHAPTER 1 


1. The Development of Oil Incendiary Bombs, R. P. 

Russell, OSRD 382, OEMsr-183, Projects CWS-21 
and B-204, Report 176, Standard Oil Develop¬ 
ment Co., Feb. 7, 1942. Div. 11-301.4-Ml 

2. The Development of Oil Incendiary Bombs, R. P. 

Russell, OSRD 577, OEMsr-183, Projects CWS-21 
and B-204, Report 243, Standard Oil Develop¬ 
ment Co., May 14, 1942. Div. 11-301.4-M2 

3. Bomb, Inceyidiary Oil, 6-lb., AN-M69, Specifica¬ 
tion 196-131-99D, CWS, Sept. 30, 1944. 

4. Bombs for Aircraft, TM9-1980, War Department, 
November 1944. 

5. U.S. Bombs and Fuzes, U.S. Navy Bomb Disposal 
School, Sept. 1, 1945. 

6. Round Tail Closure for the AN-M69, 6 Lb. In¬ 
cendiary Bomb, TDMR 919, R. L. Ortynsky, CWS, 
Nov. 9, 1944. 

7. Development of the M-69X Incendiary Bomb, 
OSRD 5254, OEMsr-354, Service Project CWS-/ 
21, Standard Oil Development Co., June 25, 1945. 

Div. 11-301.14-Ml 

8. Fuze, Bomb, Ml, Specification 196-131-llOD, 
CWS, July 21, 1944. 

9. Fuze, Bomb, Ml, Manufacture of. Service Direc¬ 
tive 277, CWS, Aug. 9, 1944. 

10. Effect of White Phosphorus on Ignitioyi of In¬ 
cendiary Fuels in M-56 Bombs, Ray L. Betts, 
NDRC-199, Report PDN-441, Standard Oil De¬ 
velopment Co., Oct. 8, 1942. Div. 11-303.3-Ml 

11. Investigation of the Use of WP and WPPS as 
Igniters in the AX-M69 Bomb, S. G. Ponder, 
CUMR 17, CWS, Feb. 10, 1943. 

12. The White Phosphorus Grenade in M-69 Obscura¬ 
tion Tests, H. A. Ricards, Jr., Report PDN-3360, 
Standard Oil Development Co., Mar. 13, 1945. 

Div. 11-301.147-Ml 

13. Strength of Tail Streamer Assembly of the M-69 
Bomb, W. T. Knox, Jr., Report PDN-1801, Stand¬ 
ard Oil Development Co., Nov. 24, 1943. 

Div. 11-301.141-M4 

14. Cluster, Incendiary Bomb, AN-M12 (100-Lb. 

Size) (H-6-Lb., AN-M69 Incendiary Bomb), 

Specification 196-131-131B, CWS, July 31, 1944. 

15. Cluster, Incendiary Bomb, AN-MlS (500-Lb. 

Size) (60-6-Lb., AN-M69 Incendiary Bomb), 

Specification 196-131-126C, CWS, Nov. 24, 1944. 

16. Cluster, Aimable Incendiary Bomb, E28 (500 Lb. 

Size) (38-6-Lb., AN-M69 Incendiary Bombs), 

Specification 196-131-292, CWS, July 7, 1944. 

17. Operational Suitability Test of Cluster, Aimable 
Incendiary Bomb, H6, C. H. Seefeldt, Board 


Project 3931C471.6, Army Air Forces, June 20, 
1945. 

18. Second Test of Incendiary Bombs on Abandoned 
Farm Houses and Barns at Jefferson Proving 
Ground, John D. Armitage and Donald D. Loos, 
Ordnance Department, August 1942. 

19. Incendiary Tests at Jefferson Proving Ground, 
Madison, Indiana, TDMR 416, R. L. Ortynsky 
and S. G. Ponder, CWS, Aug. 5, 1942. 

20. The E-6R2 Cluster, J. C. Roediger, Report PDN- 

2206, Standard Oil Development Co., Mar. 3, 
1944. Div. 11-301.15-M2 

21. Test of Clusters, Aimable, M69 Incendiary Bombs, 
Board Project (M-5) 140, Army Air Forces, Apr. 
29, 1944. 

22. Penetration of M-50, M-69 and M-69X Bombs 

into Typical Rhineland Structure, OEMsr-354, 
Report PDN-1201, Standard Oil Development 
Co., Apr. 15, 1945. Div. 11-304.21-Ml 

23. Tests of Incendiary Bombs AN-M50A1, A1SI-M52, 
AN-M5Jtf and M69 at Dugway Proving Ground, 
J. R. Adams, CWS, H. C. Hottel, NDRC, TDMR 
713, July 1943. 

24. German Industrial Structures. Their Construc¬ 
tion and Probable Penetration by Incendiary 
Bombs, OEMsr-354, Report PDN-1558, Standard 
Oil Development Co., Sept. 11, 1943. 

Div. 11-304.21-M3 

25. Penetration of M-69 on Industrial Targets in 
Aimable Clusters, W. T. Knox, Jr., Report PDN- 
2574, Standard Oil Development Co., June 7, 1944. 

Div. 11-301.142-Ml 

26. Penetration of the AN-M69 and M69X Incendiary 
Bombs into Japanese Structures When Released 
from Aimable Clusters, E. H. Lewis, J. E. Martin, 
and H. A. Ricards, Jr., DPGSR 39, CWS, Dec. 
20, 1944. 

27. Penetration and Performance Tests of Small In¬ 

cendiary Bombs in a Typical Central German 
StrucUire, OSRD 5522, OEMsr-354, Service 
Project CWS-21, Standard Oil Development Co., 
July 30, 1945. Div. 11-304.21-M6 

28. The Comparative Effectiveness of Small In¬ 

cendiary Bombs on Industrial Targets, Charles 
S. Keevil, OSRD 6189, OEMsr-21, Service Proj¬ 
ect CWS-21, Report IEP/9, Edgewood Arsenal, 
Oct. 3, 1945. Div. 11-304.2-M3 

29. Evaluation of Incendiary Fuels in German Attic 

and Sub-Attic Structures, OEMsr-354, Report 
PDN-3950, Standard Oil Development Co., Sept. 
28, 1945. Div. 11-304.21-M7 


229 


23U 


BIBLIOGRAPHY 


30. Test of Incendiary Bomb M69 Fired Statically 
ill the Predetermined Locations in Japanese Type 
Structures, DPGSR 18, J. R. Adams, W. S. 
Guthmann, and E. H. Lewis, CWS, Jan. 17, 1944. 

31. Incendiary Tests in Experimental Japanese Room, 
C. S. Keevil, OSRD 5120, Report IEP/8, NDRC, 
May 26, 1945. 

32. Japan—Incendiary Attack Data, S. de Palma 
and Raymond H. Ewell, Army Air Forces, Oct. 
15, 1943. 

33. M69 Bomb Requirements for Attack of Japanese 
Targets, TDMR 801, J. R. Adams and H. C. 
Hottel, CWS, Jan. 24, 1944. 

34. Incendiary Attack of Japanese Cities, Supple¬ 
ment to Japan—Incendiary Attack Data, October, 
1943, Raymond H. Ewell, Army Air Forces, Aug. 
29, 1944. 

35. Incendiary Attack on Japanese Cities, H. G. 
Montgomery, Jr., Board Project (T-l)34, Army 
Air Forces, Sept. 1, 1944. 

36. “Area Bombing Wrecks Jap Home Industry,” 
Impact, Army Air Forces, April 1945, Vol. Ill, 
No. 4, pp. 10-23. 

37. “Fire Blitz. Progress Report on the Incendiary 
Bombing of Japan,” Impact, Army Air Forces, 
August 1945, Vol. Ill, No. 8, pp. 18-39. 

38. “Air Victory over Japan,” Impact, Army Air 
Forces, September-October 1945, Vol. Ill, No. 9. 

39. Oil Incendiary Bomb, M-69X. Description of As- 
sembly Methods Used in Semicommercial Pro¬ 
duction, OEMsr-354, Report PDN-3700, Standard 
Oil Development Co., June 20, 1945. 

Div. 11-301.4-M7 

40. Development of the M-69X Incendiary Bomb, 
OSRD 5254a, OEMsr-354, Service Project CWS- 
21, Supplementary Report 4000, Standard Oil 
Development Co., Sept. 28, 1945. 

Div. 11-301.14-M2 

41. Test of Incendiary Bomb M69X, E. M. Downs, 
Board Project 4216C471.6, Army Air Forces, 
Apr. 12, 1945. 

42. M-69X Flight Tests, W. T. Knox, Jr., Report 

PDN-3823, Standard Oil Development Co., July 
31, 1945. Div. 11-301.143-Ml 

43. M-69X Functioning in the Day and Night Flare 

Corporation Pilot Plant, W. T. Knox, Jr., Re¬ 
port PDN-3824, Standard Oil Development Co., 
July 31, 1945. Div. 11-301.14.3-M2 

44. Functioning and Dispersion of M69X Bomb 
When Released from Aimable Clusters into a 
Ground Target, E. H. Lewis, J. E. Martin, and 
H. A. Ricards, DPGSR 38, CWS, Dec. 11, 1944. 

45. Test of E48 Cluster of Eight M69X and Thirty 
M74 Incendiary Bombs, FE 1-8, CWS, Mar. 27, 
1945. 

46. Fragmentation of the U.S. MSG (M69X) Ex¬ 
plosive Incendiary Bomb, A. C. Whiffer, MAP/ 
45/ACW, Road Research Laboratory, December 
1942. 


47. M-69X Waterproofing, W. T. Knox, Jr., Report 

PDN-2650, Standard Oil Development Co., June 
28, 1944. Div. 11-301.145-Ml 

48. High Altitude Flight Tests of Aimable Clusters 
for AN-M69 Bomb, OSRD 3761, OEMsr-354, 
Service Project CWS-21, Report PDN-2460, 
Standard Oil Development Co., June 10, 1944. 

Div. 11-301.144-M3 

49. Cluster Using E23 Adapter, TB-CW-19, War 
Department, Nov. 3, 1944. 

50. Cluster, Aimable, Inceiidiary Bomb, E46 (500 Lb. 
Size) (38-6 Lb., AN-M69), Specification 196-131- 
287, CWS, Jan. 1, 1945. 

51. Adapter, Aimable Cluster, E23, Specification 196- 
131-282, CWS, Feb. 10, 1945. 

52. The E46R1 Cluster of AN-M69 Incendiary Bomb, 
CWS, Feb. 20, 1945. 

53. Development of Aimable Cluster Adapter E23R2, 
500 Lb., for Incendiary Bombs AN-M69 and M74, 
S. Q. Kline, R. E. Patchel, L. D. Homan, and 
C. T. Mitchell, TDMR 1004, CWS, Mar. 21, 1945. 

54. Design and Development of the E-19 Incendiary 
Bomb, E. B. Hershberg, OSRD 4784, OEMsr-179 
and OEMsr-257, Service Project CWS-21, Har¬ 
vard University, Factory Mutual Research Corp., 
and Morgan Construction Co., Mar. 8, 1945. 

Div. 11-301.15-M8 

55. Design and Development of E19 Incendiary 
Bomb, OSRD 4784a, Harvard University, June 
15, 1945. 

56. Evaluation of Incendiary Bombs in Furnished 
Rooms, N. J. Thompson, OSRD 1502, Factory 
Mutual Research Corp., June 4, 1943. 

57. Comparative Incendiary Effectiveness of the 
E-19 and M-50 Incendiary Bombs, Norman J. 
Thompson and Morrill Dakin, OSRD 5023, 
OEMsr-257, Seiwice Project CWS-21, Factory 
Mutual Research Corp., Apr. 30, 1945. 

Div. 11-301.15-M9 

58. Rate of Cooling for 500-lb. Cluster of 5-lb. Oil 

Incendiary Bombs, H. A. Ricards, Jr., Report 
PDN-121, Standard Oil Development Co., May 
25, 1942. Div. 11-301.4-M4 

59. Test of Incendiary Munitions at Huntsville 
Arsenal, Alabama, S. G. Ponder and J. E. Gilbert, 
TDMR 401, CWS, June 1942. 

60. Incendiary Tests at Huntsville Arsenal, Alabama, 
June 3 to 6, 1942, N. F. Myers, Report PDN-145, 
Standard Oil Development Co., June 10, 1942. 

Div. 11-301.5-Ml 

61. Description and Specifications for the 5- and 6.5- 

pound Oil Incendiary Bomb (Third Progress Re¬ 
port), OEMsi‘-183, NDRC Project 199, July 8, 
1942. Div. 11-301.4-M5 

62. Service Tests of the 5- and 6-Lb. Oil Incendiary 
Bomb at Jefferson Proving Groiind, July 9 to 22, 
1942, N. F. Myers, W. T. Knox, Jr., and G. L. 
Matheson, Report PDN-222R, Standard Oil De¬ 
velopment Co., July 27, 1942. Div. 11-301.4-M6 



BIBLIOGRAPHY 


231 


63. Incendiary Bomb Tests at Jefferson Proving 
Ground, July 9 to 22, 191^2, Raymond H. Ewell, 
Louis F. Fieser, and others, July 28, 1942. 

Div. 11-301.17-M2 

64. Penetration Tests of Incendiary Munitions, 
TDMR 384, R. L. Ortynsky, CWS, August 1942. 

65. Loiv Temperature Ignition of Incendiary Fillings 
in the Bomb, Incendiary 6 Lb., M56, TR 7, S. G. 
Ponder, CWS, Sept. 30, 1942. 

66. Test of M52 and M56 Incendiary Bombs, AAFPGC 
Proof Department, Army Air Forces, Feb. 11, 
1943. 

67. The Use of Cellocotton in the M69 Bomb. Memo¬ 
randum on Work Done at Kodak Park, OEMsr- 
538, Eastman Kodak Co., Feb. 15, 1943. 

Div. 11-301.146-M2 

68. Use of Cellocotton in the M-69 Bomb, G. L. Mathe- 

son and Park H. Miller, Jr., OEMsr-354, Report 
PDN-950, Standard Oil Development Co., Feb. 15, 
1943. Div. 11-301.146-Ml 

69. Use of Napalm in the M69, 6 Lb. Incendiary 
Bomb, TDMR 571, R. L. Ortynsky, CWS, Mar. 
4, 1943. 

70. Characteristics of Aluminum Soap Gels of the 
Napalm Type (Fourth Progress Report), Ray 
L. Betts and N. F. Myers, OSRD 1345, Standard 
Oil Development Co., Apr. 15, 1943. 

71. Third Harvard Wind Tunnel Test on M-69 Bomb, 
F. R. Russell and N. F. Myers, Report PDN- 
973, Standard Oil Development Co., Apr. 21, 1943. 

Div. 11-301.141-Ml 

72. Small Incendiary Bomb, Oil Type (5-10 Lb.), 
W. S. Guthmann and T. M. North, DPGSR 3, 
CWS, April 1943. 

73. The M-69 Flight Stability Tests, J. C. Roediger, 

Report PDN-1301, Standard Oil Development 
Co., May 7, 1943. Div. 11-301.141-M2 

74. Fourth Harvard Wind Tunnel Tests, A. Beer- 

bower, Report PDN-1480, Standard Oil Develop¬ 
ment Co., July 27, 1943. Div. 11-301.141-M3 

75. Incendiary Oil, Solid and Viscous, Firing Be¬ 
havior and Gardner Consistencies of Napalm 
Type Fillings for the M69 Bomb, TDMR 694, 
W. H. Bauer, CWS, Aug. 20, 1943. 

76. Report on Test No. 9 (1218US), RC (F) Pan 3a/35, 
Building Research Station, September 1943. 

77. Commentary on Incendiary Tests at Dugway 
Proving Ground, Utah, May 17 to Jidy 16, 19^3, 

OEMsr-354, Report PDN-1566, Standard Oil De¬ 
velopment Co., Sept. 13, 1943. Div. 11-304.21-M4 

78. Report on Tests Nos. lOA, lOB, and IOC (SI9IU3), 
RC(F)Pan 3a/38, Building Research Station, 
October 1943. 

79. Fifth Harvard Wind Tunnel Tests, A. Beerbower, 

Report PDN-1847, Standard Oil Development 
Co., Nov. 29, 1943. Div. 11-301.141-M5 

80. Bombing Tables for Clusters Incendiary Bomb, 
AN-M12 and AN-M13, BT 6-A-2, Ordnance De¬ 
partment, Jan. 3, 1944. 


81. First Report on Incendiary Bomb Tests in Ger¬ 
man-Type Attics, RC(F)Pan 3a/61, Building 
Research Station, February 1944. 

82. The Practical Performance Testing of Small In¬ 
cendiary Bombs, Part II, RC(F)Pan 3a/66, 
Building Research Station, April 1944. 

83. Developme7it, Manufacture a7id Proof Test of 

10,000 M-69 Cluster, Type E-6R2, H. A. Ricards, 
Jr., W. T. Knox, Jr., and others. Report PDN- 
2109, OEMsr-354, Standard Oil Development Co., 
Apr. 15, 1944. Div. 11-301.144-M2 

84. Penetratio7i of Imitatio7i Bumnese Structures by 
U. S. Type AN-M69 Incendiary Bombs, Note 
MAP/117/KLCF, Road Research Laboratory, 
May 1944. 

85. Secoyid Report on hiceyidiary Bomb Tests in 
Germayi-Type Attics, RC(F)Pan 3a/78, Build¬ 
ing Research Station, June 1944. 

86. Bombs, AN-M69, Loading and Assembly, CWS 
Directive 280, CWS, Oct. 21, 1944. 

87. Test of American M69 Bomb hi B.R.S. Fire Test 
Building on 8th Septeynber 1944-, IBTP/Report/ 
95, Building Research Station, November 1944. 

88. First Report on Incendiary Boynb Tests in Jap¬ 
anese Domestic Buildings, IBTP Report/111, 
Building Research Station, February 1945. 

89. Test of First Production Lot of AN-M69 In- 
cendiary Boynbs (Kilgore Mfg. Co.), W. G. Franz 
and J. F. McCanne, TDMR 1097, CWS, July 25, 
1945. 

90. High Huynidity Surveilkmce Tests of M-69 Boynbs 
ayid Clusters, G. L. Matheson, Report PDN-3924, 
Standard Oil Development Co., Sept. 10, 1945. 

Div. 11-301.145-M2 

91. Stabilizatioyi of the AN-M69 Bomb Released from 
Quick Opening Clusters, J. E. Martin and W. G. 
Baird, Jr., TDMR 1167, CWS, Nov. 2, 1945. 

92. Use of High Explosives in Small Incendiary 
Bomb. Pittsburgh Visit May 15, 1942, W. T. 
Knox, Jr., Report PDN-128, Standard Oil De¬ 
velopment Co., May 28, 1942. 

Div. 11-301.17-Ml 

93. Lethal Explosive Charge for M-56 Bomb, W. T. 
Knox, Jr., NDRC Project 199, Report PDN-429, 
Standard Oil Development Co., Oct. 5, 1942. 

Div. 11-301.5-M2 

94. Tests Coyiducted on Incendiary Prograyn at Dug¬ 
way Proving Grouyid, Simpson Springs, Utah, be¬ 
tween Augyist 3 and October 20, 1943, H. A. 
Ricards, Jr., OEMsr-354, Report PDN-1764, 
Standard Oil Development Co., Nov. 5, 1943. 

Div. 11-301.1-Ml 

95. Tests of M69X Incendiary Boynbs at Dugway 
Proving Grouyid, Septeynber 19-Noveynber 10, 
1943, E. H Lewis, DPGSR 15, CWS, Dec. 22, 1943. 

96. Striking Velocity of M-69's from Aimable 
Clusters, A. Beerbower, Report PDN-1822, Stand¬ 
ard Oil Development Co., Nov. 26, 1943. 

Div. 11-301.144-Ml 



232 


BIBLIOGRAPHY 


97. Aerodunamic Characteristics of the NDRC C-1 
U20 Lb. Aimable Clusters Incendiary Bombs, Na¬ 
tional Bureau of Standards, Dec. 1, 1943. 

98. Aerodynamic Characteristics of the E6R2 In¬ 
cendiary Cluster Bomb, National Bui'eau of 
Standards, Jan. 7, 1944. 

99. Bombing Table for Cluster, Aimable, 500 Lb., 
Ml8(E6R2), BT 500-K-2, Ordnance Department, 
May 18, 1944. 

100. Supplementary Tests of Clusters, Aimable, for 
M69 Incendiary Bombs, D. C. Miller, Board 
Project (M-5) 140a, Army Air Forces, July 27, 
1944. 

101. Bomb Clusters Using E6R2 Adapters, TB-CW- 
16, War Department, Sept. 16, 1944. 

102. M-69 Stability from E6R2 Aimable Cluster, W. T. 
Knox, Jr., Report PDN-2960, Standard Oil De¬ 
velopment Co., Oct. 4, 1944. 

Div. 11-301.144-M4 

103. Bombing Table for Cluster, Aimable, 500 Lb., 
Elf6, BT 500-Q-l, Ordnance Department, October 
1944. 

104. Experiments ^vith Incendiary Mixtures. Fire Test 
Striictxire and Development of Incendiary Bombs, 
Norman J. Thompson, OSRD 657, OEMsr-257, 
Service Project CWS-21, Report 277, Factory 
Mutual Research Corp., June 24, 1942. 

Div. 11-301.3-M5 

105. Report of Burning Tests, Factory Mutual Re¬ 
search Corp. and Harvard University, Nov. 21, 

1942. Div. 11-301.5-M3 

106. Flight Tests on Experimental Incendiaries at 
Edgeu'ood Arsenal, Feb. 17, 1943. 

Div. 11-301.17-M3 

107. Experiments tvith Alternate Fillings for Bomb 
Incendiary, 9-ponnd E-1, Morrill Dakin, OEMsr- 
257, Factory Mutual Research Corp., Aug. 23, 

1943. Div. 11-301.16-Ml 

108. The E-19 (Formerly E-1) Magnesium Bomb and 
Its Components, Louis F. Fieser and E. B. Hersh- 
berg. Harvard University, Oct. 27, 1943. 

Div. 11-301.15-Ml 

109. Incendiary Bomb Fillings for Industrial Targets, 
Norman J. Thompson and Morrill Dakin, OSRD 
2048, OEMsr-257, Service Project CWS-21, Fac¬ 
tory Mutual Research Corp., Nov. 23, 1943. 

Div. 11-301.16-M2 

110. Test of E9 Incendiary Bomb, AAFPGC Proof 
Department Serial 1-43-76, Army Air Forces, 
Nov. 9, 1943. 

111. Preliminary Field Tests of Bomb, Inceyidiary, 
Oil, hO Lb., E9, W. A. Frantz, TDMR 819, CWS, 
Mar. 6, 1944. 

112. Develojnnent of Incendiary Fuels, Rush F. Mc- 
Cleary and Bill L. Benge, OSRD 3762, OEMsr- 


898, Service Project CWS-21, The Texas Co., 
June 10, 1944. Div. 11-301.15-M4 

113. The E-9 Bomb in E-53 Cluster Bomb Bay Load¬ 
ing, W. S. Quimby, Oct. 2, 1944. 

Div. 11-301.15-M5 

114. The E-53 Cluster. Its Release fro7n a Fighter 
Plane, W. S. Quimby, Feb. 7, 1945. 

Div. 11-301.15-M6 

115. E-9 Bomb Penetration Tests at Eglin Field, 
Florida, W. S. Quimby, Feb. 24, 1945. 

Div. 11-301.15-M7 

116. Cluster E-53, lU, E-9 (Inert) Incendiary Bombs, 
CWS, Apr. 5, 1945. 

117. E-53 Cluster Tests, Dugway Proving Ground, 
Jidy 19, 19U5, July 1945. Div. 11-301.15-MlO 

118. Static G Test of E-53 Cluster of lU E-9 Bombs 

in E-26 Adapters, S. N. Arnold, Foster-Wheeler 
Corp., July 6, 1945. Div. 11-301.15-Mll 

119. Development of Medium Sized Incendiary Bomb, 

Final Report on the Development of ^O-Pound In¬ 
ceyidiary Bomb, E-9, OEMsr-898, The Texas Co., 
Oct. 15, 1945. Div. 11-301.15-M12 

120. Flight Stability of Bomb Incendiary, 30 Lb., E3, 
J. R. Adams, Test Report 9, Chemical Warfare 
Service, Oct. 4, 1942. 

121. Comparison Tests on New Ignitors and Bursters. 
A Report on Tests Using Three M-i6A2 Bombs 
Fired on Soldiers Field, October 1, 19U2, E. B. 
Hershberg, Harvard University, Oct. 13, 1942. 

Div. 11-303.3-M2 

122. E20, 500 Lb., Cast-Iron Incendiary Bomb, R. L. 
Ortynsky, TDMR 929, CWS, Nov. 24, 1944. 

123. Cellulose Wadding (Cellocottoyi) yvith Gasoline 
as a Fuel for a 500-lb Incendiary Bomb, Norman 
J. Thompson, OEMsr-257, Factory Mutual Re¬ 
search Corp., July 28, 1943. Div. 11-301.161-Ml 

124. Gasoline-Cellocotton Filling for 500-Pound In¬ 
cendiary Bomb, Norman J. Thompson, OSRD 
1702, OEMsr-257, Service Project CWS-21, Fac¬ 
tory Mutual Research Corp., Aug. 11, 1943. 

Div. 11-301.161-M2 

125. Test of Bomb, Incendiary 500 Lb. E22, J. R. 
Adams, TDMR 816, CWS, Mar. 8, 1944. 

126. The E-22 500-lh Bomb Incendiary, Tail Ejection 

Type, Norman J. Thompson, OEMsr-257, Service 
Project CWS-21, Factory Mutual Research Corp., 
May 23, 1944. Div. 11-301.15-M3 

127. Test of Bomb, Incendiary, 500 Lb., E22 (Modi¬ 
fied), J. R. Adams and W. H. Daiger, TDMR 
968, CWS, Jan. 24, 1945. 

128. Test of 2 Lb. Plastic Bomb, J. R. Adams, TDMR 
342, CWS, Jan. 22, 1942. 

129. Development of a Plastic Incendiary Bomb, T. S. 
Carswell, H. K. Nason and others, OSRD 6621, 
OEMsr-198, Service Project CWS-21, Monsanto 
Chemical Co., Feb. 21, 1946. Div. 11-301.13-Ml 



BIBLIOGRAPHY 


233 


CHAPTER 2 


1. Recommendations for Filling and Firing the 100 
Lb. Oil Incendiary Bomb, Louis F. Fieser, OSRD 
587, Harvard University, May 25, 1942. 

2. Recommended Specifications for the WP-TNT 
Burster for the 100-lb Bomb, Louis F. Fieser, 
Harvard University, July 24, 1942. 

Div. 11-301.11-M2 

3. Dry Loading of White Phosphorus into Burster 
Tubes, Howard Adler, OSRD 765, OEMsr-296, 
Projects CWS-21 and B-246, Report 303, Victor 
Chemical Works, July 24, 1942. 

Div. 11-301.11-Ml 

4. Assembly of Burster and Igniter in MU7A1 and 
AN-Mlf7A2 Incendiary Bombs, TB-CW-10, War 
Department, July 15, 1944. 

5. Igniter, AN-M9, Specification 196-131-277A, CWS, 
Oct. 11, 1944. 

6. Burster, AN-MIS, Specification 96-131-113, CWS, 
Dec. 7, 1944. 

7. Bomb, Incendiary, 500-Lb. M76(T2E1), TB-CW-4, 
War Department, Apr. 4, 1944. 

8. Incendiary Bomb Tests at Jefferson Proving 
G)-ound, July 9 to 22, 19U2, Raymond H. Ewell, 
Louis F. Fieser, and others, July 28, 1942. 

Div. 11-301.17-M2 

9. Incendiary Tests at Jefferson Proving Gro^ind, 
Madison, Indiana, TDMR 416, R. L. Ortynsky 
and S. G. Ponder, CWS, Aug. 5, 1942. 

10. Second Test of Incendiary Bombs on Abandoned 
Farm Houses and Barns at Jefferson Proving 
Ground, John D. Armitage and Donald D. Loos, 
Ordnance Department, August 1942. 

11. Comparison Test of M-12 and M-13 Bursters, 
E. W. McIntosh, Board Report (M-5)123, Army 
Air Forces, June 12, 1944. 

12. Test of M 47 A 2 Incendiary Bomb with Modified 
M13 Burster Fuze, E. W. McIntosh, Board Proj¬ 
ect (M-5)120, Army Air Forces, June 30, 1944. 

13. Comparisoyi of M-12 and M-13 Bursters in the 

M- 47 A 2 ,100-lb. Incendiary Bomb, R. L. Ortynsky, 
Alan L. Kling, and S. Murray Jones, OSRD 4068, 
Service Project CWS-21, Report IEP/3, Aug. 30, 
1944. Div. 11-301.11-M3 

14. Harvard Candle. A Pocket Incendiary Munition, 

Louis F. Fieser, OEMsr-179, Harvard University, 

Feb. 25, 1942. Div. 11-301.21-Ml 

15. Hand Incendiaries Tested at Edgewood Arsenal, 

Edwin A. Blair, Factory Mutual Research Corp., 
Oct. 8, 1942. Div. 11-301.22-Ml 

16. Tests of Sabotage Incendiaries, NDRC Project 

457, OEMsr-257, Factory Mutual Research Corp., 
Oct. 26, 1942. Div. 11-301.23-M2 


17. Observations on the Performance of Incendiary 
Candles at Edgeivood. Tests of November 30, 
19U2, H. C. Hottel, S. P. Lovell, and Harris M. 
Chadwell, November 1942. Div. 11-301.21-M2 

18. Comparison Tests of Hand Incendiaries, OEMsr- 
257, Factory Mutual Reseai’ch Corp., Jan. 6, 1943. 

Div. 11-301.23-M3 

19. Starter, Fire, Ml, Specification 196-131-97C, 
CWS, Oct. 27, 1944. 

20. Vest-Pocket Time Delay Incendiary, Louis F. 
Fieser, OSRD 1211, OEMsr-179, Service Project 
CWS-21, Harvard University, Feb. 19, 1943. 

Div. 11-301.23-M5 

21. Evaluation Tests of FM Sabotage Incendiary, 

OEMsr-257, Factory Mutual Research Corp., 
Jan. 15, 1943. Div. 11-301.22-M2 

22. Development of SDO as an Incendiary Material 
Particularly as a Hand Incendiary, M. S. Kha- 
rasch and F. H. Westheimer, OSRD 677, Uni¬ 
versity of Chicago, July 6, 1942. 

23. Report of Test of Fire Starters E-Jf and E-5, 
George E. Miles and J. F. McCanne, Chemical 
Munitions Section, Aug. 28, 1942. 

Div. 11-301.23-Ml 

24. Design of the E-16 Allway Fuse for the AN-M69 
Incendiary Bomb, T. L. Wheeler and Max Knobel, 
OSRD 5209, OEMsr-242, Service Project CWS-21, 
Arthur D. Little, Inc., June 15, 1945. 

Div. 11-301.12-Ml 

25. Phosphorus Ignition, T. M. Beck, Victor Chemical 
Works, June 8 and 17, 1942. 

26. Red Phosphorus Incendiary Bomb Ml (Leaf), 
J. S. Carson, TDMR 484, CWS, Dec. 23, 1942. 

27. Sensitized Celluloid Fire Leaves, Charles A. 
Kraus, OSRD 1202, OEMsr-57, Service Project 
CWS-11, Brown University, Feb. 16, 1943. 

Div. 11-301.23-M4 

28. Modified M-52 Two-Pound Magnesium Bomb for 
Use against Japan, E. B. Hershberg and Morrill 
Dakin, OSRD 4521, OEMsr-179 and OEMsr-257, 
Service Project CWS-21, Harvard University and 
Factory Mutual Research Corp., Jan. 1, 1945. 

Div. 11-301.1-M2 

29. Modified M-50 Incendiary Bomb and Develop¬ 

ment of Test Target, Norman J. Thompson and 
Alan L. Kling, OSRD 4601, OEMsr-257, Service 
Project CWS-21, Factory Mutual Research Corp., 
Jan. 19, 1945. Div. 11-301.5-M6 

30. The AN-M-52 Bomb Incendiary. Optimum Veloc¬ 
ity for One-Story Japanese Dwellings, Norman 
J. Thompson and Edwin A. Blair, OEMsr-257, 
Service Project CWS-21, Factory Mutual Re¬ 
search Corp., June 8, 1944. Div. 11-301.5-M4 


(WWiluiLm T iAi ri 




234 


BIBLIOGRAPHY 


CHAPTER 3 


1. Comparative Tests of Various Incendiary Mix¬ 
tures (Report to Sept. 10, 1941), Louis F. Fieser, 
OEMsr-25; Projects CWS-21 and B-117, Harvard 
University, Sept. 17, 1941. Div. 11-301.3-Ml 

2. Comparative Tests of Various Incendiary Mix¬ 
tures. Part II, Comparison of Magnesmm, Ther¬ 
mite, SDO-Sodium Nitrate and a Gum Incen¬ 
diary, Louis F. Fieser, OSRD 173, OEMsr-25, 
Service Project CWS-21, Report 111, Harvard 
University, Nov. 10, 1941. Div. 11-301.3-M2 

3. Comparative Tests of Various Incendiary Mix¬ 
tures. Part III, Preliminary Observations on the 
Influence of the Rubber Concentration and on 
the Effect of Finely Powdered Nitrate, Louis F. 
Fieser, OEMsr-25, Service Project CWS-21, Re¬ 
port 113, Harvard University, Nov. 10, 1941. 

Div. 11-301.3-M3 

4. Comparative Tests of Various Incendiary Mix- 

tures. Part IV, Improvements in the Test Pro¬ 
cedure ayid Evaluation of Different Types of 
Rubber, Louis F. Fieser, OSRD 275, Projects 
CWS-21 and B-186, Report 132, Harvard Uni¬ 
versity, Dec. 8, 1941. Div. 11-301.3-M4 

5. Experiments with Incendiary Mixtures. Fire Test 
Structure and Development of Incendiary Bombs, 
Norman J. Thompson, OSRD 657, OEMsr-257, 
Service Project CWS-21, Report 277, Factory 
Mutual Research Corp., June 24, 1942. 

Div. 11-301.3-M5 

6. Tests of Sabotage Incendiaries, NDRC Project 

457, OEMsr-257, Factory Mutual Research Corp., 
Oct. 26, 1942. Div. 11-301.23-M2 

7. Comparison Tests of Hand Incendiaries, OEMsi’- 
257, Factory Mutual Research Corp., Jan. 6, 1943. 

Div. 11-301.23-M3 

8 . Evaluation Tests of EM Sabotage Inceyidiary, 

OEMsr-257, Factory Mutual Research Corp., Jan. 
15, 1943. Div. 11-301.22-M2 

9. Development of SDO as an Incendiary Material, 
Particularly as a Hand Incendiary, M. S. 
Kharasch and F. H. Westheimer, OSRD 677, 
University of Chicago, July 6, 1942. 

10. The Development of Oil Incendiary Bombs, R. P. 

Russell, OSRD 382, OEMsr-183, Projects CWS-21 
and B-204, Report 176, Standard Oil Develop¬ 
ment Co., Feb. 7, 1942. Div. 11-301.4-Ml 

11. Development of Incendiary Fuels, Rush F. Mc- 

Cleary and Bill L. Benge, OSRD 3762, OEMsr- 
898, Service Project CWS-21, The Texas Co., 
June 10, 1944. Div. 11-301.15-M4 

12. Report of Buryiing Tests, Factory Mutual Re¬ 

search Corp. and Harvard University, Nov. 21, 
1942. Div. 11-301.5-M3 

13. Modified M-50 Incendiary Bomb and Development 
of Test Target, Norman J. Thompson and Alan 
L. Kling, OSRD 4601, OEMsr-257, Service Proj¬ 


ect CWS-21, Factory Mutual Research Corp., 
Jan. 19, 1945. Div. 11-301.5-M6 

14. Incendiary Bomb Fillings for Indxistrial Targets, 

Norman J. Thompson and Morrill Dakin, OSRD 
2048, NDCrc-231, OEMsr-257, Service Project 
CWS-21, Factory Mutual Research Corp., Nov. 
23, 1943. Div. 11-301.16-M2 

15. Evaluation of Incendiary Fuels and Bombs on 

Industrial Building Occupancies, Norman J. 
Thompson and Alan L. Kling, OSRD 4468; 
OEMsr-257; Service Project CWS-21, Report 
lEP, 4, Factory Mutual Research Corp., Dec. 15, 
1944. Div. 11-304.2-Ml 

16. Design and Testing of a Simple Target Structure 

to Simulate Typical Industrial Incendiary Cen¬ 
ters, Norman J. Thompson and Alan L. Kling, 
OSRD 4469, OEMsr-257, Project lEP 5, Service 
Project CWS-21, Factory Mutual Research 
Corp., Dec. 15, 1944. Div. 11-304.2-M2 

17. Comparative Incendiary Effectiveness of the E-19 
and M-50 Incendiary Bombs, Norman J. Thomp¬ 
son and Morrill Dakin, OSRD 5023, OEMsr-257, 
Service Project CWS-21, Project Report IEP/7, 
Factory Mutual Research Corp., Apr. 30, 1945. 

Div. 11-301.15-M9 

18. The Comparative Effectiveness of Small Incendi¬ 

ary Bombs on Industrial Targets, Charles S. 
Keevil, OSRD 6189, OEMsr-21, Service Project 
CWS-21, Report lEP^ 9, Edgewood Arsenal, Oct. 
3, 1945. Div. 11-304.2-M3 

19. Penetration of M-50, M-69 arid M-69X Bombs 

into Typical Rhineland Structure, OEMsr-354. 
Repoi-t PDN-1201, Standard Oil Development 
Co., Apr. 15, 1943. Div. 11-304.21-Ml 

20. Penetration and Performance Tests of Small In¬ 

cendiary Bombs in a Typical Central German 
Structure, OSRD 5522, OEMsr-354, Service Proj¬ 
ect CWS-21, Standard Oil Development Co., July 
30, 1945. Div. 11-304.21-M6 

21 . Evaluation of Incendiary Fuels in German Attic 

and Sub-Attic Stmctures, OEMsr-354, Report 
PDN-3950, Standard Oil Development Co., Sept. 
28, 1945. Div. 11-304.21-M7 

22. Evaluation of Incendiary Bombs in Furnished 
Rooms, N. J. Thompson and E. A. Blair, OSRD 
1502, Factory Mutual Research Corp., June 4, 
1943. 

23. Design and Construction of Typical German and 
Japanese Test Struchires at Dugway Proving 
Ground, Utah, OEMsr-354, Report PDN-1340, 
Standard Oil Development Co., May 27, 1943. 

Div. 11-304.21-M2 

24. Tests of Incendiary Bombs AN-M50 Al, AN-M52, 
AN-M5i. and M69 at Dugway Proving Ground, 
J. R. Adams, CWS, and H. C. Hottel, NDRC, 
TDMR 713, July 1943. 

25. Tests Conducted on Incendiary Program at Dug- 




BIBLIOGRAPHY 


235 


tvay Provivg Ground, Siinpso7i Sprhigs, Utah, 
between August 3 and October 20, 19It3, H. A. 
Ricards, Jr., OEMsr-354, Report PDN-1764, 
Standard Oil Development Co., Nov. 5, 1943. 

Div. 11-301.1-Ml 

20. Tests of M69X Incendiary Bombs at Dugway 
Proving Ground, September 19-November 10, 

1943, DPGSR 15, E. H. Lewis, CWS, Dec. 22, 

1943. 

27. Tests of Incendiary Bomb M69 Fired Statically 
in Pre-Determined Locations in Japanese Type 
Structures, J. R. Adams, \V. S. Guthmann, and 
E. H. Lewis, DPGSR 18, CWS, Jan. 17, 1944. 

28. Incendiary Tests in Experimental Japanese Room, 

Charles S. Keevil, OSRD 5120, Service Project 
CWS-21, Repoi’t lEP, 8, Edgewood Arsenal, May 
20, 1945. Div. 11-304.21-M5 

29. Comparison Test of M-12 and M-13 Bursters, 

E. W. McIntosh, Board Report (M-5)123, Army 
Air Forces, June 12, 1944. 

30. Prototype Target Building, W. H. Daiger, TDMR 
978, CWS, Feb. 14, 1945. 

31. The Inflammability of Wood as Affected by Mois¬ 
ture Content, Richard E. Messing, OSRD 4007, 
Service Project CWS-21, Report lEP 2, Office 
of Field Service, Aug. 30, 1944. Div. 11-304.11-Ml 

32. Moisture Content of Wood in Japan, H. C. Hottel, 

Nov. 14, 1944. Div. 11-304.11-M2 

33. Burning Tests of Vertical Pla^iks, Norman J. 
Thompson and Alan L. Kling, OEMsr-257, Fac¬ 
tory Mutual Research Corp., Nov. 27, 1944. 

Div. 11-304.1-M3 

34. Moisture Content of Wood Incendiary Test Struc¬ 
tures, H. A. Ricards, Jr., Report PDN-3150, 
Standard Oil Development Co., Dec. 18, 1944. 

Div. 11-304.11-M3 

35. The Effect of Moisture on Ignition and Burning 
Characteristics of Douglas Fir, Norman J. 
Thompson and Alan L. Kling, OSRD 4797, 
OEMsr-257, Service Project CWS-21, Report 
lEP 0, Factory Mutual Research Corp., Mar. IG, 

1945. Div. 11-304.11-M4 

3G. Studies in. Wood Moisture Content, George R. 48. 
Stanbury, Raymond H. Ewell, and Richard F. 
Messing, OSRD 4988; Service Project CWS-21, 

Report lEP 6, Edgewood Arsenal, Apr. 27, 1945. 

Div. 11-304.11-M5 

• 50 

37. Ignitability of Various Woods, Norman J. Thomp- 

son and Morrill Dakin, OEMsr-257, Factory Mu¬ 
tual Research Corp., June 21, 1943. 51. 

Div. 11-304.1-M2 


38. Missio7i Analysis, Report MA-1, Operations 
Analysis Section, Twenty-First Bomber Com¬ 
mand, July 15, 1945. 

39. Analysis of Osaka Urban Area Attack, JTG 
Weapon Analysis Memorandum 11, Army Air 
Forces, Mar. 14, 1945. 

40. Bombing Accuracy, Report BA-1, Operations 
Analysis Section, Twenty-First Bomber Com¬ 
mand, July 21, 1945. 

41. Report on Bombing Accuracy of Night Incendiary 
Missions, Bombing Accuracy Report BA-2, Oper¬ 
ations Analysis Section, Twenty-First Bomber 
Command, Aug. 6, 1945. 

42. Tests for Determining Incendiary Value of 
Bombs and Bomb Fuels, Eugene B. Gerry, OSRD 
4066, Service Project CWS-21, Aug. 30, 1944. 

Div. 11-301.5-M5 

43. The Development of Oil Incendiary Bombs, R. P. 

Russell, OSRD 577, OEMsr-183, Projects CWS-21 
and B-204, Report 243, Standard Oil Develop¬ 
ment Co., May 14, 1942. Div. 11-301.4-M2 

44. The Use of Cellocotton in the M-69 Bomb. Memo¬ 
randum on TForA: Done at Kodak Park, OEMsr- 
538, Eastman Kodak Co. [?], Feb. 15, 1943. 

Div. 11-301.146-M2 

45. German Industrial Structures. Their Construc¬ 
tion and Probable Penetration by Incendiary 
Bombs, OEMsr-354, Report PDN-1558, Standard 
Oil Development Co., Sept. 11, 1943. 

Div. 11-304.21-M3 

46. Comparison of M-12 and M-13 Bursters in the 

M-47A2, 100-lb Incendiary Bomb, R. L. Ortynsky, 
Alan L, Kling, and S. Murray Jones, OSRD 4068, 
Service Project CWS-21, Report IEP '3, Aug. 30, 
1944. Div. 11-301.11-M3 

47. Wood Flammability under Various Conditions of 
Irradiation, H. C. Hottel, OSRD 432, Projects 
CWS-21 and B-205, Report 195, Massachusetts 
Institute of Technology, Mar. 3, 1942. 

Div. 11-304.1-Ml 

Effects of Weapons on Targets, Volume 1, OSRD 
4918, Report EWT-1, AN-23 Group, Apr. 5, 1945. 

Effects of Weapons on Targets, Volume 2, OSRD 
5045, Report EWT-2, AN-23 Group, May 5, 1945. 

Effects of Weapons on Targets, Volume 3, OSRD 
5176, Report EWT-3, AN-23 Group, June 5, 1945. 

Effects of Weapons on Targets, Volume 4, OSRD 
5321, Report EWT-4, AN-23 Group, July 5, 1945. 


CHAPTER 4 


1. Report of Ad Hoc Committee on Flame Throwers, 
George A. Richter, Eastman Kodak Co., Revised: 
July 28, 1942. Div. 11-302-M3 

Modification of Portable Flame Thrower for 


Thickened Fuels, N. F. Myers, G. H. Garraway, 
and others, OSRD 983, OEMsr-390, OEMsr-661, 
and OEMsr-667, Projects CWS-10, B-270, B-367, 
and others. Report 391, Standard Oil Develop- 


2. 



236 


BIBLIOGRAPHY 


ment Co., Factory Mutual Research Corp., and 
Nuodex Products Co., Oct. 12, 1942. 

Div. 11-.302.12-M2 

3. Development of Flame Throwers, Service Units 
and Thickened Fuels, OSRD 6376, OEMsr-390, 
Service Project CWS-21, Report PDN-4027, 
Standard Oil Development Co., Oct. 31, 1945. 

Div. 11-302-M5 

4. Use of Flame on Japanese Bunkers, OSRD 2090, 
OEMsr-390, Service Project CWS-10, Standard 
Oil Development Co., Dec. 4, 1943. 

Div. 11-302.51-Ml 

5. Portable Flame Throiver Ml and MlAl, TM3- 
375, CWS, May 1943. 

6. Memo on CWS-NDRC Committee Meeting — 
Portable Flame Thrower Design, CWS, Aug. 27, 
1942. 

7. Portable Flame Throivers E2 and E3, Infantry 
Board, Fort Benning, Ga., May 13, 1944. 

8. Manual on the Operation and Maintenance of 
the Portable Flame Thrower, E-2, OEMsr-390, 
Service Project SPCWT-161, Report PDN-2057, 
Standard Oil Development Co., Feb. 15, 1944. 

Div. 11-302.11-M6 

9. Comparative Tests of Portable Flame Throwers, 
Armored Board, Mar. 3, 1944. 

10. Development of Portable Flame Throiver, E-2, 
OSRD 3574, OEMsr-390, Service Project CWS-10, 
Standard Oil Development Co., May 4, 1944. 

Div. 11-302.11-M7 

11. Phosphorus-Sulphur Flame Thrower Fuel, T. L. 
Wheeler and L. B. Arnold, Jr., OSRD 5355, 
OEMsr-242, Service Project CWS-21, Arthur D. 
Little, Inc., June 15, 1945. Div. 11-303.13-Ml 

12. Thickened EWP Fuels and Ejection Devices for 
Eutectic White PhosjJiorus Fuels, T. L. Wheeler 
and A. Bogrow, OSRD 5524, OEMsr-242, Service 


Project CWS-10, Arthur D. Little, Inc., Aug. 15, 
1945. Div. 11-303.13-M3 

13. Thickened Eutectic White Phosphorus Fuels and 
Ejection Devices for EWP Fuels (Supplemen¬ 
tary Report), T. L. Wheeler and J. J. Clancy, 
OSRD 5524a, OEMsr-242, Sei’vice Project CWS- 
10, Arthur D. Little, Inc., Oct. 22, 1945. 

Div. 11-.303.13-M4 

14. Comparative Tests of Portable Flame Throivers, 
Project 532, Armored Board, Fort Knox, Ky., 
Mar. 23, 1944. 

15. Memo on CWS-NDRC Committee Meeting, N. F. 
Myers, Standard Oil Development Co., Oct. 5, 
1942. 

16. Development of Improved Portable Flame 
Thrower, Design E-2. Meeting of CWS-NDRC 
Committee, January 18 to 19, 1943, T. Loew, 
Arthur L. Brown, and N. F. Myers, January 1943. 

Div. 11-302.11-Ml 

17. Design and Constinction of Model E-2 Portable 
Flame Thrower, G. H. Garraway, Report PDN- 
959, Standard Oil Development Co., Feb. 15, 1943. 

Div. 11-302.11-M2 

18. Improved Portable Flame Thrower, Model E-2, 
G. H. Garraway, Report PDN-1238, Standard 
Oil Development Co., Apr. 21, 1943. 

Div. 11-302.11-M3 

19. Model E-2 Portable Flame Throiver, N. F. Myers, 

Report PDN-1584, Standard Oil Development 
Co., Sept. 2, 1943. Div. 11-302.11-M4 

20. New Portable Flame Thrower Equipment, Project 
DMS 416, Army Engineers, Fort Belvoir, Va., 
Sept. 16, 1943. 

21. Revisions to E-2 Portable Flame Thrower, M. D. 
Haworth, Report PDN-1612, Standard Oil De¬ 
velopment Co., Sept. 18, 1943. Div. 11-302.11-M5 


CHAPTER 5 


1. Memorandum of Meeting of Group at MIT, Tues¬ 

day, March 3, 1942, to Discuss Flame Throwers, 
H. C. Hottel, Massachusetts Institute of Tech¬ 
nology, March 1942. Div. 11-302-Ml 

2. Design and Development of Large Experimental 
Flame Thrower, D. C. Elliott, OSRD 1952, 
OEMsr-470, Service Project CWS-10, Gilbert and 
Barker Manufacturing Co., Oct. 25, 1943. 

Div. 11-302..3-M1 

3. Development of Flame Throwers Service Units 
and Thickened Fuels, OSRD 6376, OEMsr-390, 
Service Project CWS-21, Report PDN-4027, 
Standard Oil Development Co., Oct. 31, 1945. 

Div. 11-302-M5 

4. Development of Flame Throwers (Monthly Prog¬ 

ress Report for period from July 15 to Aug. 15, 
1942), OEMsr-390, Standard Oil Development 
Co., Aug. 15, 1942. Div. 11-303-Ml 


5. Field Tests on Flame Throwers, Model C 

(Monthly Progress Repox’t covering period from 
Apr. 15 to May 15, 1943), Hugh Harvey, OEMsr- 
916, Service Project CWS-10, Shell Development 
Co., May 15, 1943. Div. 11-303-M3 

6. Study of Mechanized Flame Throwers (Monthly 
Progress Report), R. D. Dawson, Shell Develop¬ 
ment Co., June 22, 1943. 

7. Study of Mechanized Flame Throwers (Monthly 
Progress Report), R. D. Dawson, Shell Develop¬ 
ment Co., July 22, 1943. 

8. Study of Mechanized Flame Throwers (Monthly 
Progress Reports covering period from May 15 to 
August 15, 1943), R. D. Dawson, OEMsr-916, 
Service Project CWS-10, Shell Development Co. 

Div. 11-303-M4 

9. Development of Flame Throwers (Monthly Prog¬ 
ress Report covering period from Sept. 15 to Oct. 



BIBLIOGRAPHY 


237 


15, 1942), OEMsr-390, Standard Oil Development 
Co., Nov. 15, 1942. Div. 11-303-M2 

10. Mobile Flame Thrower, Model Q, G. H. Garraway, 

Report PDN-1158, Standard Oil Development 
Co., Apr. 6, 1943. Div. 11-302.323-Ml 

11. Use of Flame on Japanese Bunkers, OSRD 2090, 
OEMsr-390, Service Project CWS-10, Standard 
Oil Development Co., Dec. 4, 1943. 

Div. 11-302.51-Ml 

12. Performance of Thickened Fuels in Flame 

Thrower, Model E-7(Q), Ray L. Betts, Report 
PDN-2105, Standard Oil Development Co., Feb. 
14, 1944. Div. 11-303.12-M6 

13. Flame Thy'oiver, Mechanized, E-7-7, Installed in 
Light Tank, M-SAl, OSRD 5125, OEMsr-390, 
Service Project CWS-10, Standard Oil Develop¬ 
ment Co., May 29, 1945. Div. 11-302.323-M10 

14. Development and Field Use of E-7-7 Mechanized 

Flame Thrower, OSRD 6012, OEMsr-390, Service 
Pi’oject CWS-10, Standard Oil Development Co., 
Sept. 12, 1945. Div. 11-302.322-M7 

15. Flame Throwers, Mechayiized, E-12-7R1 histalled 
in Medium Tank, M-iAl, OSRD 5126, OEMsr- 
390, Service Project CWS-10, Standard Oil De¬ 
velopment Co., May 29, 1945. Div. 11-302.322-M4 

16. The M-4-5(E-12-7Rl) Mechanized Flayyie Thrower 
histalled in M-UAl or M-UAS Medhmi Tanks, 
OSRD 6350, OEMsr-390, Service Project CWS- 
10, Standard Oil Development Co., Oct. 31, 1945. 

Div. 11-302.322-M10 

17. The E-14^-7R2 Mechanized Flayne Thrower In¬ 

stalled in LVT-Al Amphibious Tank, OSRD 
6351, OEMsr-390, Service Project CWS-10, Re¬ 
port PDN-1026, Standard Oil Development Co., 
Oct. 31, 1945. Div. 11-302.321-M3 

18. General Specificatioyis of the Model Q Tayik-Boryie 

Flayne Thrower, G. H. Garraway, Report PDN- 
1378, Standard Oil Development Co., June 2, 
1943. Div. 11-302.323-M2 

19. Ignition Studies oyi E-7 (Q) Trailer Unit, J. O. 

Collins, Report PDN-2027, Standard Oil Develop¬ 
ment Co., Jan. 28, 1944. Div. 11-303.3-M3 

20. CTFS Report-Test of Mechayiized Flame Thrower 
E7 at Edgeu'ood Arseyial, J. Senter, TDMR 807, 
Mar. 17, 1944. 

21. Armored Boai'd Report-Test on Q (E7-M5A1), 
V. O. Barnard, P-460-1, June 28, 1944. 

22. The E-7-7 Mechanized Flame Thrower in M-5A1 
Light Tank. NDRC Operational Tests, G. W. 
Engisch, Report PDN-3772, Standard Oil De¬ 
velopment Co., July 12, 1945. 

Div. 11-302.323-Mll 

23. Preliyiiinary Reports on the Operation of Mech¬ 
anized Flayne Throivers, Report 196, USAFFE 
Board, May 17, 1945. 

24. Combat Testing of Flame Thrower E-7-7 Mounted 
in Light Tank, MSAl, Thii’teenth Armored Group 
Report to Commanding General, Sixth Army, 
May 31, 1945. 


25. Navy Flame Throwers, T. V. Moore, Massachu¬ 
setts Institute of Technology, Feb. 5, 1944. 

Div. 11-302.2-Ml 

26. Flame Throwers—Description ayid Instructioyis 
for Operation, Ordnance Pamphlet 1139-USN, 
USN BuOrd, June 14, 1944. 

27. Report to First Amphibious Tractor Battalion, 
FMF, Pacific Troops, III Amphibious Corps, 
Eng. S. W. Holmes, Dec. 11, 1944. 

28. The E-7 (Q)-LVT-Al Lima Locomotive Installa- 
tioyi, M. I). Haworth, Report PDN-2196, Standard 
Oil Development Co., Mar. 1, 1944. 

Div. 11-302.321-Ml 

29. Fiyial Report—Mechanized Flame Thrower, Proj¬ 
ect 3, Landing Vehicle Board, Feb. 13, 1945. 

30. Inforynatoi'y Test of LVT Flame Thrower Unit, 
SPCVD 400.112, CWS-OC-TD, May 30, 1945. 

31. Flame Thrower, Mechanized, E-H-7R2 with 
Mixer, Thickened Fuel, E-6 and Compressor, Air, 
E-8, Report PDN-3790, Standard Oil Develop¬ 
ment Co., July 20, 1945. Div. 11-302.321-M2 

32. Flame Thrower, Mechanized, Eli-7R2, TM 3-365, 
War Department, Aug. 8, 1945. 

33. Demoyistration of Mechanized Flame Thrower 
E-12-7R1 and Servicing Uyiit E-8 for Chemical 
Warfare Service, Report PDN-3370, Standard 
Oil Development Co., Feb. 22, 1945. 

Div. 11-302.322-Ml 

34. Flame Thrower, Mechanized, E-12-7R1 ayid Serv¬ 

ice Unit, Mechanized Flame Thrower, E-8, Re¬ 
port PDN-3499, Standard Oil Development Co., 
M. W. Kellogg Co., and the Davey Compressor 
Co., Apr. 2, 1945. Div. 11-302.322-M2 

35. Teclmical Manual—Flame Throiver, Mechanized, 
E12-7R1 (Installed in Medium Tanks M^Al ayid 
M4A3), TM3-360, War Department, July 20, 
1945. 

36. Field Test of E12-7R1 Mechanized Flame Thrower 
Mounted in MUAl, Mediuyn Tank, and E8 Service 
Unit Mounted in 2^2 Ton Truck, Project 627, 
Chemical Warfare Board, May 9, 1945. 

37. lyispectioyi ayid Field Operatioyial Tests of 20 

E-12-7R1 Flame Throivers, J. 0. Collins, Report 
PDN-3672, Standard Oil Development Co., June 
6, 1945. Div. 11-302.322-M5 

38. Joint CWS-NDRC Mechanized Flame Thrower 

Evaluatioyi Project, A. W. Adkins, G. A. Agoston, 
and others, OSRD 5933, OEMsr-21, Service Proj¬ 
ect CWS-10, Massachusetts Institute of Tech¬ 
nology, June 30, 1945. Div. 11-302.322-M6 

39. Fuel Recommeyidations for E-12-7R1 Flayne 

Thrower, A. W. Adkins, Edgewood Arsenal, June 
23, 1945. Div. 11-303-M5 

40. Description of C. F. Braun and Coynpany Flame 

Thrower, G. P. Klaas, C. F. Braun and Company, 
Oct. 27, 1943. Div. 11-302.323-M5 

41. Letter to T. V. Moore. Subject, “Additional In¬ 
formation about Design of Flame Thrower for 



238 


BIBLIOGRAPHY 


M-5 Tank,” G. P. Klaas, C. F. Braun and Co., 
Dec. 13, 1945. Div. ll-302,323-M6 

42. Developmeyit of Mobile Flame Throwey, G. P. 
Klaas, OSRD 5443, OEMsr-943, Service Project 
CWS-10, C. F. Braun and Co., Aug. 12, 1945. 

Div. 11-302.323-M12 

43. Demonstration of Klaas-Braun Flame Throiver, 
October 10, 19^^, Charles S. Keevil, Oct. 13, 1944. 

Div. 11-302.323-M8 

44. A Simplified Form of Flame Throwing Mech¬ 
anism, Model I, R. L. Iglehart and R. O. Dawson, 
OEMsr-916, Service Project CWS-10, Shell De¬ 
velopment Co., Mar. 15, 1944. Div. 11-302.33-Ml 

45. Mechanized Flame Thrower, Model 1-3, R. D. 

Dawson and A. S. Grundy, OSRD 4983, OEMsr- 
916, Service Project CWS-10, Shell Development 
Co., Apr. 24, 1945. Div. 11-302.33-M2 

47. Description of Indiana-Merz Flame Thrower, 
T. V. Moore, Oct. 10, 1943. Div. 11-302.323-M4 

46. Standard Oil Company of Indiana and Merz 
Engineermg Company, Mechanized Flame Throw¬ 
ers, T. V. Moore, Aug. 14, 1943. 

Div. 11-302.323-M3 

48. Development of Flame Thrower for M-5 Tank, 
OSRD 4432, OEMsr-1011, Service Project CWS- 
10, Standard Oil Co. of Indiana, Dec. 6, 1944. 

Div. 11-302.323-M9 

49. Investigation of Accident to Flame Thrower 

under Development by Standard Oil Company of 
Indiana and Merz Engineering Company, OSRD 
4374, OEMsr-1011, Service Project CWS-10, 

Standard Oil Co. of Indiana and Merz Engineer¬ 
ing Co., Nov. 30, 1944. Div. 11-302-M4 

50. The E-13-13 Flame Gun and Equipment in 
M-^Al Tank, Myles Morgan, OSRD 5711, OEMsr- 
1364, Service Project CWS-10, Morgan Construc¬ 
tion Co., Sept. 17, 1945. Div. 11-302.322-M8 

51. Letter to E. P. Stevenson, W. C. Kabrich, CWS, 
May 15, 1944. 

52. Development of Mechanized Flame Thrower 
E-13R1-13R2 in M-J^Al Tank, T. V. Moore and 
T. R. Camp, OSRD 4980, OEMsr-21 and OEMsr- 
1364, Service Project CWS-10, Massachusetts 
Institute of Technology, Apr. 30, 1945. 

Div. 11-302.322-M3 

53. Flame Throtvers, Incendiaries and Their Evalua¬ 
tion, Abbott Byfield, W. A. Klemm, and G. A. 
Agoston, OSRD 6190, OEMsr-21, Service Proj¬ 
ects CWS-10 and CWS-21, Massachusetts Insti¬ 
tute of Technology, Oct. 1, 1945. 

Div. 11-300-Ml 

54. Design of Mechanized Flame Thrower in M-UA3 

Tank Retaining 76-mni Gun, H. 0. Croft, J. M. 
Trummel, and othex’s, OSRD 6015, OEMsi’-1480, 
Service Project CWS-10, State University of 
Iowa, Sept. 30, 1945. Div. 11-302.322-M9 

55. Letter to H. M. Chadwell, NDRC. Subject, “Re¬ 
sponsibilities Related to Development of Flame 


Thrower Tank T-33,” W. C. Kabrich, SPCVD 
470.8, CWS, May 28, 1945. 

56. Preliminary Study of the Application of Pumps 
to Flame Throwers, T. V. Moore, OEMsr-21, 
Service Project CWS-10, Massachusetts Institute 
of Technology, Apr. 20, 1944. Div. 11-302.4-Ml 

57. Further Study of the Application of Pumps to 
Flame Throwers, Abbott Byfield, OEMsr-21, 
Service Project CWS-10, Massachusetts Insti¬ 
tute of Technology, Feb. 26, 1945. 

Div. 11-302.4-M2 

58. Shidies of Thickened Liquids (Monthly Pi'ogress 
Report), E. E. Bauer, and E. K. Carver, Eastman 
Kodak Co., Mar. 16, 1945. 

59. Studies of Thickened Liquids (Monthly Px'Ogi’ess 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., Api'. 14, 1945. 

60. Studies of Thickened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Cai’ver, Eastman 
Kodak Co., May 15, 1945. 

61. Studies of Thickened Liquids (Monthly Progress 
Repoi’t), E. E. Bauer and E. K. Cai’ver, Eastman 
Kodak Co., June 15, 1945. 

62. Studies of Thickened Liquids (Monthly Progi’ess 
Report), E. E. Bauer and E. K. Cai’ver, Eastman 
Kodak Co., July 24, 1945. 

63. Washington Conference January 12, 191.5, Re¬ 
port PDN-3288, Standard Oil Development Co., 
Jan. 19, 1945. 

64. Letter Report of Preliminary Test of Flame 
Thrower, Mechanized, E-11-7R2; Mixer, Thick¬ 
ened Filed, E6; and Compressor, Air, E8, 470.71 
NDER, Landing Vehicle Board, Aug. 3, 1945. 

65. CTFS Letter on Approval of Landing Vehicle 
Board Recommendations on E11-7R2 Unit, 
SPCVD 161, CWS-Technical Division, Aug. 21, 
1945. 

66. Report on E12-7R1 Flame Thrower Fuel and 
Range Performance for Manual and Theatre 
Letter, CWS-NDRC, MFTE Group, June 23, 
1945. 

67. A Comparison of Space Requirements for Flame 

Throwers Propelled by Pumps and by Compressed 
Gas, Abbott Byfield, Massachusetts Institute of 
Technology, May 7, 1945. Div. 11-302.4-M3 

68. Trip to Eastman Kodak of May 25, 1915, H. C. 

Hottel, Massachusetts Institute of Technology, 
May 26, 1945. Div. 11-302.4-M4 

69. Agreements Reached at Rochester Conference on 
Developmeyit of Pump-Operated Flame Thrower, 
August 3, 1915, H. C. Hottel, Massachusetts In¬ 
stitute of Technology, Aug. 6, 1945. 

Div. 11-302.4-M5 

70. Studies of Thickened Liquids (Monthly Progress 
Reports covering period fi’om April 15, 1943, to 
August 15, 1945), E. K. Caiwer, E. E. Bauer, and 
others, OEMsr-538, Service Projects CWS-10, 
CWS-12, and CWS-21, Eastman Kodak Co. 

Div. 11-303.1-Ml 




BIBLIOGRAPHY 


239 


CHAPTER 6 


1. Letter to Brig. Gen. W. C. Kabrich. Subject, 
“Servicing Units for Mechanized Flame Thrower,” 
N. F. Myers, Report PDN-2991, Standard Oil 
Development Co., Oct. 12, 1944. 

Div. 11-302.2-M4 

2. Modification of Portable Flame Throtver for 
Thickened Fuels, N. F. Myers, G. H. Garraway, 
and others, OSRD 983, OEMsr-390, OEMsr-661, 
and OEMsr-667, Project CWS-10, B-270, B-367, 
and others. Report 391, Standard Oil Develop¬ 
ment Co., Factory Mutual Research Corp., and 
Nuodex Products Co., Oct. 12, 1942. 

Div. 11-302.12-M2 

3. Description of Mobile Servicing Unit for Flame 

Throivers, S. H. Hulse and Ray L. Betts, Report 
PDN-2440, Standard Oil Development Co., Apr. 
29, 1944. Div. 11-302.2-M2 

4. Development of Mobile Servicing Unit for Flame 
Throwers, OSRD 4434, OEMsr-390 and OEMsr- 
1266, Service Project CWS-10, Report PDN-3000, 
Standard Oil Development Co., Dec. 7, 1944. 

Div. 11-302.2-M5 

5. Mobile Servicing Unit for Flame Throwers, 

OEMsr-390 and OEMsr-1266, Report PDN-2760, 
Aug. 23, 1944. Div. 11-302.2-M3 

6. Service Unit, E-8, for Use with Mechanized 
Flame Throivers, OSRD 5127, OEMsr-390, Serv¬ 
ice Project CWS-10, Report PDN-3500, Standard 
Oil Development Co., May 29, 1945. 

Div. 11-302.2-M8 

7. Letter Report on Service Unit, Mechanized Flame 
Thrower E8, Armored Board, Apr. 4, 1945. 

8. Development of Mobile Service Equipment for 

Mechanized Flame Throivers, OSRD 6014, 
OEMsr-390, Service Project CWS-10, Final Re¬ 
port PDN-3975, Standard Oil Development Co., 
Oct. 18, 1945 Div. 11-302.2-M9 

9. Operating Destructions for Mirer, Thickened 
Fuel Flame Thrower, EG, CWS (Unpublished). 

10. Development of Flame Throivers, Service Units 
and Thickened Fuels, OSRD 6376, OEMsr-390, 
Service Project CWS-21, Report PDN-4027, 
Standard Oil Development Co., Oct. 31, 1945. 

Div. 11-302-M5 

11. Mobile Servicing Unit, E-8. Consideration of 

Design Changes, Ray L. Betts and S. H. Hulse, 
Report PDN-3241, Standard Oil Development 
Co., Jan. 5, 1945. Div. 11-302.2-M6 

12. Production of Thickened Fuels Using Fast- 

Setting Napalm at High Temperature, OSRD 
6011, OEMsr-390, Service Project CWS-10, Re¬ 
port PDN-3900, Standard Oil Development Co., 
Aug. 31, 1945. Div. 11-303.11-M15 

13. histruction Pamphlet No. 1, Compressor, Air, 
Gasoline Engine Driven, 60 CFM, E8, CWS (Un¬ 
published) . 

14. Letter Report of Preliminary Test of Flame 


Thrower, Mechanized EH-7R2; Mixer, Thick¬ 
ened Fuel, EG; and Compressor, Air, E8, Land¬ 
ing Vehicle Board, Aug. 3, 1945. 

15. Ferro-Cleaver Brooks Mixer, E. K. Carver, Oct. 

5, 1945. Div. 11-303.2-M2 

16. Testing of Ferro Enamel Napalm Gasoline Mixer, 
Robert W. Bond, TCIR 251, CWS, Feb. 9, 1945. 

17. Self-Powered Portable Mixing Unit, C. E. Reed, 

Apr. 19, 1945. Div. 11-303.2-Ml 

18. Projector, Anti-Personnel, Tank, El, War De¬ 
partment, TB CW (32) (Tentative), Aug. 1945. 

19. The Scorpion, T. L. Wheeler and A. Bogrow, 

OEMsr-242, Service Project CWS-21, Arthur D. 
Little, Inc., Feb. 7, 1945. Div. 11-302.31-Ml 

20. Anti-Personnel Protection Device for Tanks 

(Scorpion), H. L. Allen, Armored Board, Feb. 9, 
1945. 

21. Anti-Personnel Protection Device for Tanks 

(Scorpion), P-633, L. V. Hightower, Armored 
Board, Feb. 22, 1945. 

22. Phosphorus-Phosphorus Sesquisulfide Eutectic as 

a Special Flame Thrower Fuel, T. L. Wheeler 
and A. Bogrow, OSRD 5523, OEMsr-242, Service 
Project CWS-10, Arthur D. Little, Inc., Aug. 3, 

1945. Div. 11-303.13-M2 

23. Countermeasures against Flame. Memorandum 
of Conference on Project NS-317 on September 
22 , 19UU, H. C. Hottel, Service Project NS-317, 
Arthur D. Little, Inc., Sept. 23, 1944. 

Div. 11-302.53-Ml 

24. Studies of Speeial Flame Thrower Fuels and De¬ 

velopment of Countermeasures against Flame 
Throwing Equipment (Monthly Progress Report 
covering period from January 15 to February 15, 
1945), T. L. Wheeler and A. Bogrow, OEMsr- 
242, Service Project CWS-21, Arthur D. Little, 
Inc., Feb. 19, 1945. Div. 11-302.53-M2 

25. Conning Tower Port Plugs, T. L. Wheeler and 

Roger C. Griffin, OEMsr-242, Arthur D. Little, 
Inc., May 21, 1945. Div. 11-302.52-Ml 

26. Protection of Ship Conning Towers, T. L. 

Wheeler, Roger C. Griffin, and Arthur L. Brown, 
OSRD 5356, OEMsr-242, Service Project NS- 
317, Arthur D. Little, Inc., July 19, 1945. 

Div. 11-302.52-M2 

27. Protection of Ship Conning Towers, T. L. 

Wheeler and Roger C. Griffin, OSRD 6013, 
OEMsr-242, Service Project NS-317, Arthur D. 
Little, Inc., Sept. 17, 1945. Div. 11-302.52-M3 

28. The Skink, Formerly Scorpion, Allen Latham, 
Jr., Arthur D. Little, Inc., Apr. 12, 1945. 

Div. 11-302.31-M2 

29. Thickened EWP Fuels and Ejection Devices for 

Eutectic White Phosphorus Fuels, T. L. Wheeler 
and A. Bogrow, OSRD 5524, OEMsr-242, Service 
Project CWS-10, Arthur D. Little, Inc., Aug. 15, 
1945. Div. 11-303.13-M3 



240 


BIBLIOGRAPHY 


CHAPTER 7 


1. Study of Disintegration of Liqiiid Jets in Air, 
H. C. Hottel and L. W. Russum, Nov. 23, 1941. 

Div. 11-303.42-Ml 

2. Memorandum of Meeting of Group at MIT, 

Tuesday, March 3, 194.2 to Discuss Flame Throw¬ 
ers, H. C. Hottel, Massachusetts Institute of 
Technology, March 1942. Div. 11-302-Ml 

3. Effect of Nozzle Design on the Range of Burning 
Jets, OSRD 685, E. W. Cousins, Factory Mutual 
Research Corp., July 8, 1942. 

4. Studies on Fuel Projection from Nozzles, H. C. 
Hottel, OSRD 615, OEMsr-21, Projects CWS-10 
and B-109, Report 261, Massachusetts Institute 
of Technology, June 8, 1942. Div. 11-303.43-Ml 

5. Characteristics of Fluid Jets, Interim Report No. 
4, a Photographic SUtdy of Jets on Non-New¬ 
tonian Liquids from Various Types of Nozzles, 
R. P. Frasex', J. M. Connor, and M. O. Coulter, 
Imperial College of Science, Jan. 31, 1943. 

6. Development of Flame Thrower for M-5 Tank, 
OSRD 4432, OEMsr-1011, Service Project CWS- 
10, Standard Oil Co. of Indiana, Dec. 6, 1944. 

7. Factors Governing the Performance of Flame 
Throwers, G. A. Agoston and W. A. Klemni, 
OSRD 4981, Massachusetts Institute of Tech¬ 
nology, Apr. 30, 1945. 

8. Study of Mechanized Flame Throwers (Monthly 
Progress Reports covering period from May 15 
to August 15, 1943), R. D. Dawson, OEMsr-916, 
Service Project CWS-10, Shell Development Co. 

Div. 11-303-M4 

9. Description of C. F. Braun and Company Flame 

Thrower, G. P. Klaas, C. F. Braun and Co., Aug. 
8, 1944. Div. 11-302.323-M7 

10. The E-13-13 Flayne Gun and Equipment in M-4A1 

Tank, Myles Morgan, OSRD 5711, OEMsr-1364, 
Service Project CWS-10, Morgan Construction 
Co., Sept. 17, 1945. Div. 11-302.322-M8 

11. Joint CWS-NDRC Mechanized Flame Thrower 

Evaluation Project, A. W. Adkins, G. A. Agoston, 
and others, OSRD 5933, OEMsr-21, Service Proj¬ 
ect CWS-10, Massachusetts Institute of Tech¬ 
nology, June 30, 1945. Div. 11-302.322-M6 

12. Studies of Thickened Liquids (Monthly Progi’ess 
Report), E. E. Bauer and E. K. Cai’ver, East¬ 
man Kodak Co., Feb. 15, 1945. 

13. Flame Throwers, Incendiaries and Their Evalua¬ 

tion, Abbott Byfield, W. A. Klemm, G. A. Agoston, 
OSRD 6190, OEMsr-21, Service Projects CWS-10 
and CWS-21, Massachusetts Institute of Tech¬ 
nology, Oct. 1, 1945. Div. 11-300-Ml 

14. Sttidies of Thickened Liquids (Monthly Pi’ogress 
Report), E. E. Bauer and E. K. Cai’ver, Eastman 
Kodak Co., Apr. 14, 1945. 

15. Portable Flame Thrower Nozzle Diameter, J. H. 
Carpenter and C. H. King, Jr., Massachusetts 


Institute of Technology—M.R. No. 106, CWS, 
Oct. 10, 1944. 

16. Flow of Napalm Thickened Gasoline in Pipes and 
Nozzles, A. L. Bi*own and C. W. Cousins, OSRD 
3522, OEMsr-661, Service Project CWS-10, Fac- 
toi’y Mutual Research Corp., Apr. 25, 1944. 

Div. 11-303.43-M2 

17. Properties of Thickened Liquids, R. L. Pigford, 
OSRD 4284, E. I. du Pont de Nemours and Co., 
Oct. 25, 1944. 

18. Studies of Thickeiied Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., Nov. 15, 1944. 

19. Fluid Meters, A.S.M.E., 4th Ed. 1937. 

20. Status of NDRC Projects on Flame Throwers, 
H. C. Hottel and G. H. Garraway, Repoi’t 272, 
OEMsi’-21, 167, 390, and 470; Seiwice Projects 
CWS-10, B-109, and others; OSRD 637, Massa¬ 
chusetts Institute of Technology and Standard 
Oil Development Co., June 20, 1942. 

Div. 11-302-M2 

21. Rheological Properties of Thickened Liquids, 
E. K. Carver and G. Broughton, OSRD 1113, 
Eastman Kodak Co., Dec. 7, 1942. 

22. Rheological Properties of Thickened Liquids 
(Second Repoi’t), E. K. Carver and John R. Van 
Wazer, Jr., OSRD 1389, OEMsr-538, Service 
Projects CWS-10, CWS-12, and CWS-21, East¬ 
man Kodak Co., May 7, 1943. Div. 11-303.1-M2 

23. Fragmentation of Liquids, T. H. Chilton, R. L. 
Pigford, and J. B. Tipe, OSRD 1503, E. I. du 
Pont de Nemours and Co., May 31, 1943. 

24. Properties of Thixotropic, Dilatant and Other 

Fluids (Pi’ogress Repoi’ts 10 and 11), G. Brough¬ 
ton and E. K. Cai’ver, OEMsr-538, Mar. 15 and 
Apr. 15, 1943. Div. 11-303.44-Ml 

25. U.S. Navy Mark I Flame Thrower. Effect of 

Operating Pressure and Wind on Range, J. O. 
Collins, Report PDN-2602, Standard Oil Develop¬ 
ment Co., June 19, 1944. Div. 11-303.41-M2 

26. The Effect of Wind on Flame Throiver Range, 
OEMsr-21, Service Project CWS-10, Massachu¬ 
setts Institute of Technology, Feb. 10, 1944. 

Div. 11-303.41-Ml 

27. Studies of Thickened Liquids (Monthly Progress 
Report), G. Broughton and E. K. Carver, East¬ 
man Kodak Co., Jan. 15, 1944. 

28. Use of Flame on Japanese Bunkers, OSRD 2090, 
OEMsr-390, Service Project CWS-10, Standard 
Oil Development Co., Dec. 4, 1943. 

Div. 11-302.51-Ml 

29. Report on Mechanized Flame Throwers, NDRC 
11.3 and CWS, July 15, 1945. 

30. Fuel and Nozzle Study. The E-14-7R2 Flame 
Thrower in LVT-Al Amphibious Tank, J. 0. 
Collins, Report PDN 4112, Standard Oil Develop¬ 
ment Co., Jan. 18, 1946. Div. 11-302.321-M4 






BIBLIOGRAPHY 


241 


CHAPTER 8 


1. Memorandum on Incendiaries, Louis F. Fieser, 
Harvard University, Feb. 25, 1942. 

Div. 11-30.3.11-Ml 

2. Recommendations for the Fillings and Firing of 
the 100 Lb. Oil Incendiary Bomb, Louis F. Fieser, 
OSRD 587, Harvard University, May 25, 1942. 

3. History of Napalm, Louis F. Fieser, Sept. 24, 

1942. Div. 11-303.11-M3 

4. Compound X-IOA-B, Formula No. 1, Arthur 
Minich, Nuodex Products Co., Inc., Nov. 14, 1942. 

Div. 11-303.11-M4 

5. Characteristics of Aluminum Soap Gels of the 
Napalm Type, Ray L. Betts and N. F. Myers, 
OSRD 1345, Standard Oil Development Co., Apr, 
15, 1943. 

6. Invention Report on Incendiaries, Part I, Gelled 

Fuels of the Napalm Type, Benton A. Bull, May 
1, 1943. Div. 11-303.12-M3 

7. The Stability of Incendiary Gels (First Report), 
OEMsr-538, Eastman Kodak Co., June 1, 1943. 

Div. 11-303.12-M4 

8. Incendiary Oil, Solid and Viscous, Firing Be¬ 
havior and Gardner Consistencies of Napalm 
Type Fillings for the M69 Bomb, W. H. Bauer 
and H. Barnard, TDMR 694, CWS, Aug. 20, 

1943. 

9. Letter to H. C. Hottel. Subject, “The Inhibition 
of the Oxidation of Napalm Soap,” E. R. White, 
Shell Development Co., Aug. 30, 1943. 

Div. 11-303.11-M5 

10. The Manufacture, Properties and Testing of 
Napalm Soaps, G. Broughton and Abbott By- 
field, OSRD 2036, Service Projects CWS-10 and 
CWS-21, Eastman Kodak Co., Nov. 17, 1943. 

Div. 11-303.11-M7 

11. Thickener, Napalm, CWS Specification 196-131- 
107A, CWS, Dec. 28, 1943. 

12. The Pre])aration and Properties of Alumimim 
Naphthenate Soaps, S. B. Elliott, OEMsr-882, 
Ferro Drier and Chemical Co., Jan. 3, 1944. 

Div. 11-303.11-M8 

13. Oils, Incendiary, Determination of the Consist¬ 
ency of, CWS Directive 201B, CWS, Jan. 12, 

1944. 

14. Studies of Thickened Liquids (Monthly Pi’ogress 
Report), G. Broughton and E. K. Carver, East¬ 
man Kodak Co., Jan. 15, 1944. 

15. Oil, Ineendiary, NP, Type III, CWS Specifica¬ 
tion 196-131-244, CWS, Feb. 8, 1944. 

16. Studies of Thickened Liq^cids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, East¬ 
man Kodak Co., Feb. 15, 1944. 

17. The Manufactiire, Properties and Testing of 
Napalm Soaps, G. Broughton and Abbott Byfield, 
OSRD 2036a, Service Projects CWS-10 and 
CWS-21, Eastman Kodak Co., Mar. 7, 1944. 

Div. 11-303.11-M9 


18. St^idies of Thickened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., Mar. 15, 1944. 

19. Studies of Thickened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., Apr. 15, 1944. 

20. Flame Thrower Fuels, R. D. Dawson and E. R. 
White, OSRD 3506, OEMsr-916, Service Project 
CWS-10, Shell Development Co., Apr. 20, 1944. 

Div. 11-303.12-M7 

21. Consistency of Napalm Gels, E. K. Carver and 

E. E. Bauer, OSRD 3508, OEMsr-358, Service 
Projects CWS-10 and CWS-21, Eastman Kodak 
Co., Apr. 20, 1944. Div. 11-303.12-M8 

22. Studies of Thickened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, East¬ 
man Kodak Co., May 15, 1944. 

23. Development of Incendiary Fuels, Rush F. Mc- 

Cleary and Bill L. Benge, OSRD 3762, OEMsr- 
898, Service Project CWS-21, The Texas Co., 
June 10, 1944. Div. 11-301.15-M4 

24. Aluminum Soaps for Thickening Gasoline, G. H. 
McIntyre and S. B. Elliott, OSRD 3772, OEMsr- 
882, Service Projects CWS-10 and CWS-21, Ferro 
Drier and Chemical Co., June 13, 1944. 

Div. 11-303.11-Mll 

25. Studies of Thickened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, East¬ 
man Kodak Co., June 15, 1944. 

26. Studies of Thiekened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., July 15, 1944. 

27. Studies of Thickened Liquids (Monthly Progress 
Report), E. E. Bauer, Eastman Kodak Co., Aug. 
15, 1944. 

28. Studies of Thickened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., Sept. 15, 1944. 

29. Fxmdamental Study of the Structure and Char¬ 

acteristics of Soap-Thickened Fuels (Repoi’t cov¬ 
ering period from May 1943 to June 1944), J. W. 
McBain, OSRD 4205, OEMsr-1057, Seiwice Proj¬ 
ects CWS-10 and CWS-21, Stanford University, 
June 1944. Div. 11-303.11-M10 

30. Studies of Thickened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., Oct. 15, 1944. 

31. Studies of Thiekened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., Nov. 15, 1944. 

32. Meeting to Consider Eliminating Napthenic Acids 

from the Napalm Formula, at Dumbarton Oaks, 
November 3, 19UU, E. E. Bauer, Eastman Kodak 
Co., Nov. 17, 1944. Div. 11-303.11-M12 

33. Studies of Thickened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., Dec. 15, 1944. 



242 


BIBLIOGRAPHY 


34. Fundamental Study of the Structure and Char¬ 

acteristics of Soap-Thickened Fuels (Report cov¬ 
ering period from July 1944 to December 1944), 
J. W. McBain, OEMsr-1057, Service Projects 
CWS-10 and CWS-21, Stanford University, De¬ 
cember 1944. Div. 11-303.11-M13 

35. Effect of Thickener and Gasoline Qiiality on the 

Properties of Napalm Fuels, Ray L. Betts, OSRD 
4522, OEMsr-390 and OEMsr-354, Service Pi’oj- 
ects CWS-10 and CWS-21, Standard Oil Develop¬ 
ment Co., Jan. 1, 1945. Div. 11-303.11-M14 

36. Studies of Thickened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., Jan. 15, 1945. 

37. Oil, Incendiary, NP, Type I, Specification 196- 
131-161B, CWS, Feb. 1, 1945. 

38. Studies on Thickened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., Feb. 14, 1945. 

39. Oil, Incendiary, NP, Type II, Specification 196- 
131-103C, CWS, Mar. 12, 1945. 

40. Studies on Thickened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., Mar. 15, 1945. 

41. The Effect of Drying Agents on Napalm Thick¬ 
ened Fuels, 43rd Chemical Laboratory Co., CWS, 
Mar. 16, 1945. 

42. Studies of Thickened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., Apr. 15, 1945. 

43. A New Theory and Tactic of Flame Throiver 
Warfare, 43rd Chemical Laboratory Co., CWS, 
May 7, 1945. 

44. Studies of Thickened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., May 15, 1945. 

45. Cooperative Procedure Log Reports 1-19, R. G. 
DeGray, CWS, August 1944 to May 1945. 

46. Studies of Thickened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., June 15, 1945. 

47. Manufacturing Conditions and Results of Sta¬ 
bility Tests on Selected Batches of Incendiary 
Gel, National Oil Refineries, Ltd., June 20, 1945. 

48. Studies of Thickened Liquids (Monthly Progress 
Report), E. E. Bauer and E. K. Carver, Eastman 
Kodak Co., July 15, 1945. 

49. Studies of Thickened Liquids (Monthly Progress 
Reports covering period from April 15, 1943, to 
August 15, 1945), E. K. Carver, E. E. Bauer, and 
others, OEMsi’-538, Service Projects CWS-10, 
CWS-12, and CWS-21, Eastman Kodak Co. 

Div. 11-303.1-Ml 

50. Production of Thickened Fuels Using Fast Set¬ 

ting Napalm at High Temperatures, OSRD 6011, 
OEMsr-390, Service Projects CWS-10, Report 
PDN-3900, Standard Oil Development Co., Aug. 
31, 1945. Div. 11-303.11-M15 

A Study of Aluminum Soaps for Thickening 


Gasoline, K. E. Long and John Dickenson, OSRD 
6349, OEMsr-847, Service Projects CWS-10 and 
CWS-21, Harshaw Chemical Co., Sept. 30, 1945. 

Div. 11-303.11-M16 

52. Studies of Thickened Liquids and Miscellaneous 

Flame Thi'ower Problems, E. E. Bauer and E. K. 
Carver, OSRD 6236, OEMsr-358, Service Proj¬ 
ects CWS-10, CWS-12, and CWS-21, Eastman 
Kodak Co., Oct. 23, 1945. Div. 11-303-M6 

53. The Mechanized Gardner Mobilometer, E. L. Mc- 
Millen and E. K. Carver, OSRD 6234, OEMsr- 
358, Service Projects CWS-10 and CWS-21, East¬ 
man Kodak Co., Oct. 30, 1945. Div. 11-303.12-M10 

54. Pei-formance of Peptized Napalm Fuels III (Re¬ 
port 2029), Experimental Station, Suffield, Al¬ 
berta, Canada. 

55. Aluminum Cresylate from Petroleum Cresylic 
Acids, G. C. Brock and A. G. Orr, OSRD 6237, 
OEMsr-1468, Service Project CWS-10, California 
Research Corp., Sept. 29, 1945. Div. 11-303.14-Ml 

56. Isobutyl Methacrylate Polymer NR, Specification 
196-131-119, CWS, Nov. 28, 1942. 

57. Oil Incendiary, IM, Type II, Specification 196- 
131-120, CWS, Dec. 29, 1942. 

58. Properties and Examination of IM, Type III 
Incendiary Fuel, E. C. Kirkpatrick, E. 1. duPont 
de Nemours and Co., Inc., Apr. 26, 1943. 

Div. 11-303.12-M2 

59. Oil, Incendiary, IM, Type I, Specification 196- 
131-102A, CWS, Apr. 29, 1943. 

60. Study of Chemical Warfare Service IM-1 For¬ 

mula Modifications, E. I. duPont de Nemours and 
Co., Inc., May 19, 1943. Div. 11-301.3-M7 

61. Methacrylate Interpolymers as Gasoline Thickeyi- 
ing Agents, E. C. Kirkpatrick, OSRD 3763, 
OEMsr-744, Service Project CWS-21, E. I. du¬ 
Pont de Nemours and Co., Inc., June 10, 1944. 

Div. 11-303.12-M9 

62. Synthetic Polymers as Gasoline Thickening 
Agents, E. C. Kirkpatrick, OSRD 4202, OEMsr- 
744, Service Project CWS-21, E. 1. duPont de 
Nemours and Co., Oct. 2, 1944. Div. 11-301.3-M8 

63. Isobutyl Methacrylate Polymer AE, Specification 
196-131-108A, CWS, Mar. 6, 1945. 

64. Oil, Incendiary, IM, Type III, Specification 196- 
131-145B, CWS, Mar. 28, 1945. 

65. The Development of Oil Incendiary Bombs, R. P. 
Russell, OSRD 382, Report 176, OEMsr-183, 
Service Projects CWS-21 and B-204, Standard 
Oil Development Co., Feb. 7, 1942. 

Div. 11-301.4-Ml 

66. The. Developmeyit of Oil Dicendiary Bo))tbs (Sup¬ 
plement to Report 243), R. P. Russell, OSRD 
577, OEMsr-183, Projects CWS-21 and B-204, 
Standard Oil Development Co., May 14, 1942. 

Div. 11-301.4-M3 

67. Waste-Gasoliyie-Oil Mixture for Filling the Esso 
Inceyidiary Boynb, E. A. Blair, Factory Mutual 
Research Corp., June 9, 1942. 


51. 



BIBLIOGRAPHY 


243 


(58. The Use of Cellocotton in the M-69 Bomb. Mevio- 
randnm on Work Done at Kodak Park, OEMsr- 
538, Eastman Kodak Co., Feb. 15, 1943. 

Div. 11-301.146-M2 

G9= Use of Cellocotton in the M-69 Bomb, G. L. Mathe- 
son and P. Miller, OEMsr-354, Report PI)N-950, 
Standard Oil Development Co., Feb. 15, 1943. 

Div. 11-301.146-Ml 

70. Cellulose Wadding (Cellocotton) with Gasoline as 
a Fuel for the 500-lb Incendiary Bomb, Norman 
J. Thompson, OEMsr-257, Factory Mutual Re¬ 
search Corp., July 28, 1943. Div. 11-301.161-Ml 

71. Gasoline-Cellocotton Filling for the 500-Pound 
Incendiary Bomb, Norman J. Thompson, OSRD 
1702, OEMsr-257, Service Project CWS-21, Fac¬ 
tory Mutual Research Corp., Aug. 11, 1943. 

Div. 11-301.161-M2 

72. Incendiary Bomb Fillings for Industrial Targets, 
Norman J. Thompson and Morrill Dakin, OSRD 
2048, OEMsr-257, Service Project CWS-21, Fac¬ 
tory Mutual Research Corp., Nov. 23, 1943. 

Div. 11-301.16-M2 

73. The E-22 500-lb Incendiary Bomb, Tail Ejection 

Type, Norman J. Thompson, OEMsr-257, Service 
Pi'oject CWS-21, Factory Mutual Research Corp., 
May 23, 1944. Div. 11-301.15-M3 

74. Production of Incendiaries from Acetylene. 

Polymers (DVA and SDO) (Report to Sept. 15, 
1941), Louis F. Fieser, OSRD 174, OEMsr-25, 
Projects CWS-21 and B-117, Harvard University, 
Nov. 10, 1941. Div. 11-303.12-Ml 

75. Experiments with Incendiary Mixtures. Fire Test 
Stmicture and Development of Incendiary Bombs, 
Norman J. Thompson, OSRD 657, OEMsr-257, 
Service Project CWS-21, Report 277, Factory 
Mutual Research Corp., June 24, 1942. 

Div. 11-301.3-M5 

76. Development of SDO as an Incendiary Material, 
Particularly as a Hand Incendiary, M. S. Khar- 
asch and F. H. Westheimer, OSRD 677, Univer¬ 
sity of Chicago, July 6, 1942. 

77. Letter to R. H. Ewell. Subject, "Thickened 

Fuels,” Henry Gould, Nuodex Products Co., Inc., 
Sept. 10, 1942. Div. 11-303.11-M2 

78. Development of Incendiary Mixtures, Norman J. 
Thompson, and Edwin A. Blair, OSRD 1123, 
OEMsr-257, Projects CWS-21 and B-231, Factory 
Mutual Research Corp., Jan. 13, 1943. 

Div. 11-301.3-M6 

79. Experiments ivith Alternate Fillings for Bomb 

Incendiary, 9-Pound E-1, Morrill Dakin, OEMsr- 
257, Factory Mutual Research Corp., Aug. 23, 
1943. Div. 11-301.16-Ml 

80. Exploratory Experiments on the Use of Metallic 
Sodium in Incendiaries, J. W. McBain, K. J. 
Myselsaand, G. H. Smith, Stanford University, 
Nov. 8, 1943. 

81. The Use of Fortified Fuel in Flame Throivers, 
Incendiary Bombs and Incendiary Mortars, with 


an Appendix on: Turpentine, Carbon Disidfide 
Gels as Flame Thrower Fuels, Norman J. Thomp¬ 
son, E. M. Cousins, and Edwin A. Blair, OSRD 
3196, OEMsr-257, Service Projects CWS-10 and 
CWS-21, Factory Mutual Research Corp., Jan. 
29, 1944. Div. 11-303.12-M5 

82. Studies of Special Thickened Flame Thrower 
Fuels, Fi-ederick S. Bacon and A. Bogrow, 
OEMsr-242, Service Project CWS-21, Arthur D. 
Little, Inc., Apr. 20, 1944. Div. 11-303.1-M3 

83. Preparation of Organometallic Compomids as 
Sources of Toxic Oxide Smokes and Flame- 
Thrower Fuels, H. Gilman, OSRD 314, Iowa State 
College, Jan. 9, 1942. 

84. Preparation of Triethylboron to be Used Gen¬ 
erally in Incendiaries and for Ignition of Oil on 
Water, H. Gilman, OSRD 871, Iowa State Col¬ 
lege, Aug. 7, 1942. 

85. Investigation of the Use of WP and WPPS as 
Igniters in the AN-M69 Bomb, N. Birnbaum and 
S. M. Edmonds, CUMR 17, CWS, Feb. 10, 1943. 

86. Chemical Ignition of Flame Throwers, E. C. 

Kirkpatrick, OSRD 3507, OEMsr-744, Service 
Project CWS-10, E. I. duPont de Nemours and 
Co., Inc., Apr. 20, 1944. Div. 11-303.3-M4 

87. Phospho7'us-Sulfur Flame Thrower Fuel, T. L. 

Wheeler and L. B. Arnold, Jr., OSRD 5355, 
OEMsr-242, Service Project CWS-21, Arthur D. 
Little, Inc., June 15, 1945. Div. 11-303.13-Ml 

88. Phosphorus-Phosphorus Sesquisulfide Eutectic as 

a Special Flame Thrower Fuel, T. L. Wheeler 
and A. Bogrow, OSRD 5523, OEMsr-242, Service 
Project CWS-10, Arthur D. Little, Inc., Aug. 3, 

1945. Div. 11-303.13-M2 

89. Thickened EWP Fuels and Ejection Devices for 

Eutectic White Phosphorus Friels, T. L. Wheeler 
and A. Bogrow, OSRD 5524, OEMsr-242, Service 
Project CWS-10, Arthur D. Little, Inc., Aug. 15, 
1945. Div. 11-303.13-M3 

90. Thickened Eutectic White Phosphorus Fuels and 
Ejection Devices for EWP Fuels (Supplemen¬ 
tary report), T. L. Wheeler and J. J. Clancy, 
OSRD 5524a, OEMsr-242, Service Project CWS- 
10, Arthur D. Little, Inc., Oct. 22, 1945. 

Div. 11-303.13-M4 

91. Rheological Properties of Thickened Liquids, E. 
K. Carver and G. Broughton, OSRD 1113, East¬ 
man Kodak Co., Dec. 7, 1942. 

92. Propei'ties of Thixotropic, Dilatant and Other 

Fluids (Progress Reports 10 and 11), G. Brough¬ 
ton and E. K. Carver, OEMsr-538, Mar. 15 and 
Apr. 15, 1943. Div. 11-303.44-Ml 

93. Rheological Properties of Thickened Liquids 
(Second Report), E. K. Carver and John R. Van 
Wazer, Jr., OSRD 1389, OEMsr-538, Service 
Projects CWS-10, CWS-12, and CWS-21, East¬ 
man Kodak Co., May 7, 1943. Div. 11-303.1-M2 

94. Studies of Thickened Liquids (Monthly Progress 


C’l 



244 


BIBLIOGRAPHY 


Report), E. K. Carver and G. Broughton, East¬ 
man Kodak Co., May 15, 1943. 

95. Studies of Thickened Liquids (Monthly Progress 
Report), E. K. Carver and G. Broughton, East¬ 
man Kodak Co., June 15, 1943. 

96. SUidies of Thickened Liquids (Monthly Progress 
Report), C. Wynd and G. Broughton, Eastman 
Kodak Co., July 15, 1943. 

97. Studies of Thickened Liquids (Monthly Progress 
Report), E. K. Carver, Eastman Kodak Co., Aug. 
15, 1943. 

98. Studies of Thickened Liquids (Monthly Progress 
Report), E. K. Carver, Eastman Kodak Co., 
Sept. 15, 1943. 

99. Rheological Measurements on Thickened Vesi¬ 
cants, E. K. Carver and J. R. Van Wazer, Jr., 


OSRD 1893, Eastman Kodak Co., Oct. 5, 1943. 

100. Studies of Thickened Liquids (Monthly Progress 
Report), E. K. Carver, Eastman Kodak Co., Oct. 
15, 1943. 

101. Studies of Thickened Liquids (Monthly ProgTess 
Report covering period from October 15 to No¬ 
vember 15, 1943), G. Broughton and E. K. Car¬ 
ver, OEMsr-538, Service Projects CWS-10 and 
CWS-21, Eastman Kodak Co., Nov. 15, 1943. 

Div. 11-303.11-M6 

102. Studies of Thickened Liquids (Monthly Progress 
Report), E. K. Carver, Eastman Kodak Co., Dec. 
15, 1943. 

103. Properties of Thickened Liquids, R. L. Pigford, 
OSRD 4284, E. I. duPont de Nemours and Co., 
Oct. 25, 1944. 



OSRD APPOINTEES 


DIVISION 11 


Division 11 was organized on December 9, 1942 when 
former Division B of the NDRC was broken up into 
four new Divisions, 8, 9, 10 and 11, known as the Chemi¬ 
cal Divisions. Former Division B was under the Chair¬ 
manship of Roger Adams and had ten sections, each of 
which had one or more subsections. Division 11 was 
made up of Sections B-7, B-8, part of B-9 and B-10 (to¬ 
gether with subsections B-7-b, B-7-d, B-7-e, B-8-a, B-8-b, 
B-8-C, B-8-d, B-8-e, B-8-f, B-9-a and B-9-d) of former 
Division B. Subsections B-9-b and B-9-c of Section B-9 
were later incorporated in a new Division 19. 

The list which appears below therefore shows essen¬ 


tially the organization since December 9, 1942. Although 
many changes were made during the years 1943-1945, 
the names of all appointees who held appointments to 
Division 11 at any time during this period have been 
included. In addition, the names of men who held ap¬ 
pointments in the sections and subsections of former 
Division B, but who did not have appointments to 
Division 11 following the reorganization, have been 
included so as to give a complete picture of the oi’ganiza- 
tion since the beginning of the work under NDRC. 

Section 11.3 comprises Subsections B-7-d and B-7-e 
and Section B-10 of former Division B. 


Chiefs 


R. P. Russell 


H. M. Chadwell 


E. P. Stevenson 


Tecimical Aide 

D. Churchill, Jr. 


Members 


D. Churchill, Jr. 

E. R. Gilliland 
H. C. Hottel 

H. F. Johnstone 


W. K. Lewis 
J. H. Rushton 
R. P. Russell 
T. K. Sherwood 

E. P. Stevenson 


SECTION 3 


N. F. Myers 


Chiefs 


H. C. Hottel 


R. H. Ewell 
C. C. Furnas 

S. M. Jones 


Technical Aides 


C. E. Reed 


C. S. Keevil 
R. E. Loop 
R. M. Newhall 


H. J. Billings 
E. K. Carver 
L. F. Fieser 
H. O. Forrest 
C. R. Hoover 
H. C. Hottel 
H. F. Johnstone 
C. A. Kraus 


Members 


W. E. Kuhn 
T. V. Moore 
J. D. Murch 
N. F. Myers 
J. K. Roberts 
R. P. Russell 
E. P. Stevenson 
N. J. Thompson 


245 










V 





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TV- 




CONTRACT NUMBERS, CONTRACTORS AND SUBJECT OF CONTRACTS 


Contract Numbers Name and Address of Contractor 


Subject 


OEMsr-21 (11-109) 


OEMsr-25 (11-117) 
(Superseded by 
OEMsr-179) 

OEMsr-57 (11-146) 
OEMsr-113 (11-157) 


OEMsr-167 (11-110) 
(Superseded by 
OEMsr-661) 


OEMsr-179 (11-186) 
(Replacing 
OEMsr-25) 


OEMsr-179; Sub¬ 
contract No. 1 

OEMsr-183 (11-204) 
(Superseded by 
OEMsr-354) 

OEMsr-198 (11-202) 


OEMsr-234 (11-205) 
OEMsr-242 (11-203) 


OEMsr-242; Sub¬ 
contract No. 1 


Massachusetts Institute of Technology 
Cambridge, Massachusetts 


Harvard University 

Cambridge, Massachusetts 

Brown University 

Providence, Rhode Island 

University of Chicago 
Chicago, Illinois 

Associated Factory Mutual Fire Insur¬ 
ance Companies 
Boston, Massachusetts 


Harvard University 

Cambridge, Massachusetts 


Morgan Construction Company 
Worcester, Massachusetts 

Standard Oil Development Company 
New York, New York 

Monsanto Chemical Company 
Springfield, Massachusetts 

Massachusetts Institute of Technology 
Cambridge, Massachusetts 

Arthur D. Little, Inc. 

Cambridge, Massachusetts 


William L. Gilbert Clock Corporation 
Winsted, Connecticut 


Design of Flame Thrower Nozzles; Appli¬ 
cations of Thickened Fuels; Miscellaneous 
Problems Relating to Incendiaries and 
Flame Throwers; Design and Construc¬ 
tion and Installation of a Large Flame 
Thrower in an M-4 Tank, Maintenance 
and Operation of Facilities for Testing 
of Incendiaries at Edgewood Arsenal, Md. 

Preparation and Properties of DVA as an 
Incendiary and the Development of Con¬ 
tainers for this Material. 

Development of Incendiary Devices. 

Development of the “Chicago Incendiary” 
and Possible Use of the Material Devel¬ 
oped as a U.P. Propellant. 

Development of nozzles for the projection 
of jets of combustible liquids, including 
nozzles approximately one-half inch in 
diameter suitable for use on portable 
flame throwers; studies of the general de¬ 
sign of such equipment. 

Study of organic incendiary materials and 
organic materials of possible use as U. P. 
propellants; development of new types of 
incendiary bombs; determination of the 
ballistic characteristics of such munitions 
by means of wind tunnel tests. 

Fabrication of test samples of E-1 incen¬ 
diary bomb casings and of E-1 500-lb. 
incendiary bomb assemblies. 

Development of oil incendiaries. 


Development of a nitrocellulose container 
for incendiary materials; development of 
a nitrocellulose incendiary. 

Studies of the kindling characteristics of 
wood. 

Development of weapons and munitions re¬ 
lating to chemical warfare including in¬ 
cendiaries, flame throwers and organic 
and inorganic incendiary mixtures for 
use therein; development of countermeas¬ 
ures against flame throwers; study of 
combined HE-IB attack on precision 
targets. 

Production of 600 special fuze units in 
accordance with Arthur D. Little, Inc., 
Assembly Drawing No. B1005; develop¬ 
ment of any modification that may become 
necessary as a result of the construction 
of these units. 


247 





CONTRACT NUMBERS, CONTRACTORS AND SUBJECT OF CONTRACTS 


Contract Numbers 
OEMsr-257 (11-231) 


OEMsr-296 (11-246) 

OEMsr-354 (11-204) 
(Replaced 
OEMsr-183) 
OEMsr-390 (11-270) 

OEMsr-470 (11-279) 


OEMsr-538 (11-300) 


OEMsr-538; Sub¬ 
contract No. 1. (Re¬ 
placed OEMsr-1281) 


OEMsr-538; Sub¬ 
contract No. 2 

OEMsr-661 (11-367) 
(Replaced 
OEMsr-167) 
OEMsr-677 (11-368) 


OEMsr-744 (11-364) 


OEMsr-847 (11-412) 


OEMsr-882 (11-416) 
OEMsr-898 (11-422) 


OEMsr-898; Sub¬ 
contract No. 1 


Name and Address of Contractor 

Factory Mutual Research Corporation 
Boston, Massachusetts 


Victor Chemical Works 
Chicago, Illinois 

Standard Oil Development Company 
New York, New York 

Standard Oil Development Company 
New York, New York 
Gilbert and Barker Manufacturing Com¬ 
pany 

Springfield, Massachusetts 
Eastman Kodak Company 
Rochester, New York 

Ferro Drier and Chemical Company 
Cleveland, Ohio 


Cleaver-Brooks Company 
Milwaukee, Wisconsin 

Factory Mutual Research Corporation 
Boston, Massachusetts 

Nuodex Products Company, Inc. 
Elizabeth, N. J. 


E. I. duPont de Nemours and Company, 
Ammonia Department 
Wilmington, Delaware 


Harshaw Chemical Company 
Cleveland, Ohio 

Ferro Drier and Chemical Company 
Cleveland, Ohio 

The Texas Company 
135 East 42nd Street 
New York, New York 

Foster-Wheeler Corporation 
New York, New Yoi’k 


Subject 

Development and testing of incendiary ma¬ 
terials and incendiary bombs; selection 
and provision of certain instruments re¬ 
quired for testing of incendiaries by the 
National Defense Research Committee at 
Edgewood Arsenal, Maryland. 

Development of processes for the utilization 
of phosphorus incendiaries. 

Development and production of oil incen¬ 
diaries. 

Development of flame throwers, especially 
the development of thickened fuels. 

Development of nozzles and ignition mech¬ 
anisms to be used on flame throwers. 

Study of the properties of thixotropic, dila- 
tant, and other fluids applicable to flame 
thi’owers, incendiaries and vesicants. 

Development, design and construction of 
equipment for the continuous mixing of 
dry Napalm and other thickening agents 
with hydrocarbon fuels to produce uni¬ 
form gels. 

Design and development of apparatus for 
the continuous mixing of Napalm and 
hydrocarbon fuels. 

Development of flame throwers, and, more 
particularly, attempt to improve the pres¬ 
ent portable flame thrower. 

Development of methods and agents for 
thickening fuels for use in incendiary 
bombs and flame throwers and for thick¬ 
ening vesicants, with particular emphasis 
on the application of naphthenate soaps. 

Development of agents and methods for 
thickening fuels for use in incendiary 
bombs and flame throwers and for thick¬ 
ening vesicants, with particular emphasis 
on the application of synthetic polymers. 

Formulation of aluminum soap thickening 
agents and practical methods for their 
manufacture. 

Study of aluminum soap thickening agents. 

Design, development and test of a medium¬ 
sized incendiary bomb, suitable for pre¬ 
cision aiming and adapted to efficient 
loading on American aircraft. 

Design, development and test of medium¬ 
sized incendiary bomb, suitable for pre¬ 
cision aiming and adapted to efficient 
loading on American aircraft. 


248 







CONTRACT NUMBERS, CONTRACTORS AND SUBJECT OF CONTRACTS 


Contract Numbers 

Name and Address of Contractor 

Subject 

OEMsr-898; Sub- 

Standard Products Company 

Design, development and test of a medium- 

contract No. 2 

Detroit, Michigan 
(Poi’t Clinton, Ohio) 

sized incendiary bomb, suitable for pre¬ 
cision aiming and adapted to efficient 
loading on American aircraft. 

OEMsr-916 (11-394) 

Shell Development Company 

400 Bush Street 

San Francisco, California 

Development and pi’oduction of improved 
fuels for flame throwers; development of 
flame throwers; design and development 
of mobile flame throwers. 

OEMsr-943 (11-413) 

C. F. Braun and Company 

Alhambra, California 

Design, development, construction, and dem¬ 
onstration of mobile flame throwers. 

OEMsr-1011 (11-447) 

Standard Oil Company (Indiana) 

910 S. Michigan Avenue 

Chicago, Illinois 

Design and development of mobile flame 
throwers; development of fuels for flame 
throwers; development of a field unit for 
servicing flame throwers. 

OEMsr-1011; Sub- 

Merz Engineering Company 

Design and development of mobile flame 

contract No. 1 

Indianapolis, Indiana 

throwers. 

OEMsr-1057 (11-455) 

Stanford University 

Stanford University, California 

Studies of structure and characteristics of 
soap-thickened fuels. 

OEMsr-1170 (11-470) 

Ford, Bacon and Davis, Inc. 

New York, New York 

Design and construction of test structure 
and bomb-proof shelter at Eglin Field, 
Florida. 

OEMsr-1266 (11-483) 

Davey Compressor Company 

Kent, Ohio 

Design, construction and the furnishing of 
necessary shop drawings and layouts of 
two (2) servicing units for flame throw- 

OEMsr-1281 (11-488) 

Ferro Drier and Chemical Company 

Studies of methods of field mixing of flame 

(Superseded by 
OEMsr-538, sub¬ 
contract No. 1) 

Cleveland, Ohio 

thrower fuels. 

OEMsr-1364 (11-498) 

Morgan Construction Company 
Worcester, Massachusetts 

Design of several different types of tank- 
mounted flame throwers; construction and 
installation in a M4A1 tank of an ex¬ 
perimental flame thrower; construction 
of twenty (20) special flame guns. 

OEMsr-1386 (11-499) 

Consolidated Engineering Company 
Baltimore, Maryland 

Construction of three buildings in accord¬ 
ance with certain drawings, entitled 
“Preliminary Layout-Test Laboratory for 
NDRC at Edgewood Arsenal.” 

OEMsr-1468 (11-512) 

California Research Corporation 

200 Bush Street 

San Francisco, California 

Development of methods (1) for preparing 
aluminum cresylate from cresylic acids 
derived from petroleum and (2) for pre¬ 
paring satisfactory gels by the addition 
of such aluminum cresylate and fatty 
acids to hydrocarbon fuels. 

OEMsr-1480 (11-514) 

University of Iowa 

Iowa City, Iowa 

Studies and experimental investigations in 
connection with (a) the design and con¬ 
struction of a flame thrower kit and the 
installation of such kit in a medium tank 
which will retain the main armament and 
(b) the construction of several additional 
flame thi’ower kits for installation in the 
field; engineering and consulting services 
for the construction of additional kits by 
Chemical Warfare Service contractors. 


249 












SERVICE PROJECTS 


The projects listed below were transmitted to the Executive 
Secretary, NDRC, from the War or Navy Department through 
either the War Department Liaison Office for NDRC or the 
Office of Research and Inventions (formerly the Coordinator of 
Research and Development), Navy Department. 


Service 

Project 

Number 

Title 

CWS-10 

CWS-12 

Army Projects 

Flame Thrower: (a) fuel composition (b) nozzle design. 
Materials for Thickening and Increasing the Viscosity of 
Vesicants. 

CWS-21 

Study of Incendiary Materials. 

NO-164 

NS-317 

Navy Projects 

Rockets and Rocket Projectors. 

The Development of Countermeasures Against Flame-Throwing 
Equipment. 

AN-23 

Army-Navy Projects 

Studies of Combined HE-IB Attack on Precision Targets. 














INDEX 


The subject indexes of all STR volumes are combined in a master index printed in a separate volume. For 
access to the index volume consult the Army or Navy Agency listed on the reverse of the half-title page. 


Air compressor, Clark Bros., 148 
Air-drag cables for E53 bomb 
cluster, 36 

Allegheny Ballistics Laboratory, 
102 

Aluminum alcoholates, 205 
Aluminum Company of America, 99 
Aluminum cresylate (camgel), 204 
Aluminum dilaurate, 216 
Aluminum palmitate, 192 
Aluminum soaps, 167, 192, 204, 
215-216 

see also Napalm 
Aluminum stearate, 167 
Amines in gels, 205 
AmiJhibious tanks, flame throwers, 
116 

AN-incendiary bomb types; see 
under model number of in¬ 
dividual bombs 

Arthur D. Little, Inc., 49, 156-165 
Atelectasis (respiratory lesion), 
159 

Ball viscosimeter, 201 
Bickford fuze, 35, 38 
Blackmer pump, 201 
Bombing effectiveness, 85-94 

attacks on Japanese cities, 90-94 
building and roof types, 87 
comparison of bombs, 86-90 
density of bomb hits within an 
area, 86 
Are spread, 87 

occupancy of floor area, 88, 89 
prediction, 89 
roof height effect, 88, 89 
Bombs, 7-94 
British, 7 

gasoline gel (oil bombs) 

E3; 40 
E9; 33-40, 67 
E20; 41 
E22; 41-42 

M47; 44-46, 81, 82, 88, 199, 206 
M69; 8-30, 49-94, 199, 206 
M69X, 21-27, 68-72 
German, 7 
magnesium 
E19; 32, 33 
M50; 52, 63-69, 81, 89 
M52; 51-52, 69 
plastic bomb, 42 
pyrotechnic gel 


M74; 55, 63-64, 68, 69, 79-82 
M76; 46 
thermate 
M54; 69 

Bombs, bursters, 45 
Bombs, clusters, 13-19, 23-41 
aimable clusters for M69 bomb, 
27-33 

British, 30 

E18 aimable cluster, 30 
E28; 13 
E36; 13, 16 

E53 for E9 bomb, 36-40 

M12; 13 

M13; 13 

M19; 13, 15, 30 

M21 (E74), 23 

Bombs, fuels; see Incendiary fuels 
Bombs, fuzes; Bickford fuze, 35, 38 
E16 fuze, 50 
Ensign-Bickfoi’d, 11 
M'l fuze, 11 
Bombs, igniters, 45 
Bombs, sizes, 7 
Bombs, tests, 53-56 

airborne tests, 55, 59, 75-78 
analysis of destruction, 85-94 
comparison test of bombs, 70 
effect of target material, 69 
effect of target’s moisture con¬ 
tent, 79 

evaluation of fuels, 56-58, 67 
height tests, 53 
ignition of wood, 82-85 
impact test, 53 
objectives of tests, 53 
on farm buildings, 69 
on German houses, simulated, 19, 
70-76 

on house furniture, 72-75 
on industrial targets, 62-64, 80- 
82 

on Japanese structures, 75-86 
on roof sections, 57 
penetration test, 53, 69 
probability of bomb firing, 63-64 
probability of starting Are, 64, 67 
selection of test target, 56 
uncontrollable fires, 74 
use of air gun, 54-55 
use of high-speed movies, 54 
use of mortar guns, 54 
Boron trifluoride, 212-213 


Brascon (aluminum soap thick¬ 
ener) , 204 

British; aluminum soap thickener, 
204 

bomb cluster. No. 20; 30 
incendiary bombs, 7 
Ronson Lighter flame thrower, 
103 

Snapshot model flame thrower, 
96 

Brown University, 50 
Bursters for bombs, 45 

Cl aimable bomb cluster, 28 
Camgel (aluminum soap thick¬ 
ener), 204 

Cellulose-bodied fuels, 209 
Cellusolve, 204 

Chan and chol (aluminum soap 
thickener), 204 

Chemical Warfare Service; E16 
fuze, 50 

incendiary bomb tests, 69 
M2 incendiary leaf, 51 
M14-M5 burster-igniter, 46 
M19 aimable cluster, 30 
Chicago University; Chicago hand 
incendiaries, 48 
sabotage incendiaries, 46 
tests on incendiary materials, 57 
Clark Bros, air compressor, 147 
Clark-Hodsman viscosimeter, 217 
Cleaver-Brooks flame-thrower fuel 
mixer, 150-153 
Cluster adapters, 36 
Clusters for bombs; see Bombs, 
clusters 
Cresol, 204 
Cresylic acid, 156 

Davey Compressor Co., 147 
Dehydrating agents for fuels, 200 
Diethyl zinc, 212 

Dugway Proving Ground; aii’borne 
incendiary tests, 75-78 
E9 bomb, performance, 38 
fire-fighting tests, 76 
tests on M52 bomb, 51 
du Pont de Nemours & Co.; bomb 
fillings, 206 

momentum of a jet, 187 

El anti-personnel tank flame 
thrower, 156-158 

E2 portable flame thrower, 97-100 


253 


254 


INDEX 


E3 oil bomb, 40 
E6 fuel mixer, 147, 148 
E6R2 adapter for bomb clusters, 13 
E7 flame gun, 106-110 
E7-7 flame thrower, 110-112 
E7R1 flame gun, 109 
E7R2 flame gun, 109 
E8 air compressor, 150 
E8 flame thrower, 122-124 
E8 service unit for flame thrower, 
147-148 

E9 flame thrower, 126-128 
E9 oil bomb, 33-40, 67 
ballistic characteristics, 38 
design details, 35 
dispersion pattern, 38 
E53 cluster, 36 
flghter planes, use in, 39 
ignition process during fall, 36- 
40 

performance data, 38 
test on filling for bomb, 67 
Ell fuel mixing unit, 153-155 
E12-7R1 flame thrower, 120-122 
E13-13 flame thrower, 128-132 
E13R1-13R2 flame thrower, 132- 
135 

E14-7R2 flame thrower, 116-120 
E16 all-ways fuze, 49 
E16 portable flame thrower, 102 
E18 aimable cluster; comparison 
with British clusters, 30 
components, 28 
E19 magnesium bomb, 32, 33 
E19-19 flame thrower, 135-139 
E20 flame gun, 109 
E20 oil bomb, 41 
E20-20 flame thrower, 140-143 
E21 adapter for bomb clusters, 13 
E22 oil bomb, 41-42 
E26 adapter for E53 bomb cluster, 
36 

E28 bomb cluster, 13, 16, 27 
E36 bomb cluster, 13, 16 
E46 (M19) bomb cluster, 13, 15, 30 
E53 cluster of E9 bombs, 36 
E74 (M21) bomb cluster, 23 
Eakins precipitation technique for 
napalm,193 

Eastman Kodak Co.; flame throw¬ 
ers, pump-operated, 143, 172 
range of unignited jet, 186 
Edgewood Arsenal; bomb tests on 
industrial targets, 62-64, 81 
bomb test on Japanese room, 77- 
80 

tests on E12-7R1 flame thrower, 
122 


tests on Mark I flame thrower, 
116 

Edgewood Ml gel, 225 
Eglin Field; bomb test on factory 
sti’ucture, 80-81 
E9 bomb, performance, 38 
M69 bomb, performance, 16 
tests on bomb bursters, 45 
Electrically controlled flame 
thrower, 157 

Emphysema (respiratory lesion), 
159 

Ensign Bickford fuze, 11, 22 
Ethylaluminum sesquibromide, 213 
Eutectic fuel for incendiaries, 213 
EWP (phosphorus-phosphorus ses- 
quisulfide), 101, 156, 213-214 

Factory Mutual Research Corp.; 
bomb tests on house furni¬ 
ture, 74-75 

bomb tests on industrial targets, 
60 

E22 bomb, 41, 42 
flame throwers, mechanized, 103 
fortified fuel for E19 bomb, 210 
sabotage incendiaries, 46-48 
tests on flame-thrower nozzles, 
167 

tests on incendiary materials, 57 
tests on penetrating power of 
bombs, 69 

thermite mixtures for bombs, 52 
Ferro Enamel Co., 199 
Ferro-Cleaver Brooks mixing unit, 
150-153 

Fire extinguishment, water fog 
curtains, 160 

Fire fighting tests with M69 bomb, 
76 

Fire starters, 47-49 
Flame attack, countermeasures, 
159-165 

Flame effect on people and animals, 

158- 159 

Flame guns; E7; 106-110 
E13; 128-135 
E19; 138 
E20; 109 

Flame throwers, countermeasures, 

159- 161 

Flame throwers, design, 166-191 
fuel consistency, 177 
fuel system, 167-172 
ignition system, 186 
nozzle design, 166-169, 176, 179 
photography, use of, 166, 169 
pressure losses in propulsion sys¬ 
tems, 172-177 


pump propulsion, 172 
valve design, 169, 171 
Flame throwers, electrically con¬ 
trolled, 157 

Flame throwers, fuel; see Incendi¬ 
ary fuels 

Flame throwers, fuel mixers, 149- 
156 

E6 mixer, 149 
E8; 147 

Ell mixing unit, 153-155 
Ferro-Cleaver Brooks mixing 
unit, 150-153 

Mark I mixing unit, 155-156 
Flame throwers, mechanized, 103- 
146 

characteristics, 103 
E7-7 for light tanks, 110-112 
E8 for M5 light tank, 122-124 
E9 for light tank, 126-128 
E12-7R1 for medium tanks, 120- 
122 

E13-13 for medium tanks, 128- 
132 

E13R1-13R2 in medium tank, 
132-135 

E14-7R2 for amphibious tanks, 
116-120 

E19-19 in medium tank, 135-139 
E20-20 in medium tank, 140-142 
experimental models, 103-106 
1-3 for vehicular mounting, 124- 
126 

Navy Mark I for landing boats, 
112-116, 198 

pump-operated, in medium tank, 
103-106, 142-145 

Flame throwers, portable, 95-102 
British Ronson Lighter, 103 
comparison of E2 and MlAl; 98 
El anti-personnel tank projector, 
156-158 
E2; 95-100 

expendable flame thrower, 101- 
102 

MlAl; 96 

M2-2 flame thrower, 100 
Flame throwers, range factors, 
166-191 

air temperature, 190 
definition of range, 166 
degree of fuel ignition, 168, 183, 

190 

fluid pressure at nozzle, 172-177, 
179 

fuel consistency, 177, 198 
gun elevation, 182-184 
internal changes in gel, 169, 184- 

191 



INDEX 


255 


jet break up, 166-169, 225 
nozzle design, 166-169 
obstructions in fuel line, 169 
pressure losses, 169 
range prediction of ignited jets, 
190 

valve design, 169, 171 
wind intensity and direction, 182- 
184 

FM sabotage incendiary, 48 
Fog applicators for fire extinguish¬ 
ment, 160 

Foster-Wheeler Corp., 34 
Foxboro recording psychrometer, 
162 

FRAS (aluminum stearate-thick¬ 
ened fuel), 167 
Froude number, 184-191 
Fuel mixtures; see Flame throw¬ 
ers, fuel mixers 

Fuel trailer for E9 flame throwers, 
126 

Fuels, cellulose-bodied, 13, 209 
Fuels, fortified, 210 
Fuels, napalm thickened, 192-205 
Fuels, peptized; amines, 200 
super-peptized fuels, 200 
xylenol, 199-200 
Fuels, self-igniting, 212-215 
aluminum compounds, 212 
bismuth compounds, 212 
diethyl zinc, 212 
nitrated arsenic and lead deriva¬ 
tives, 212 

organometallic compounds, 212- 
213 

phosphorus-phosphorus sesqui- 
sulfide, 213-214 
triethyl boron, 212 
Fuels, thickeners, 192-226 
see also Gels, characteristics 
aluminum alcoholates, 205 
aluminum cresylate, 204 
aluminum soaps, 203, 215-216 
brascon, 204 
camgel, 204 
chan and chol, 204 
Edgewood Ml gel, 225 
fuller’s earth, 215 
geletrol, 204 
metalex, 204 

methacrylate thickening agents, 
206-207 

napalm, 192-205 
oleopalm, 192 
palmene, 192 
pseudoplastic gel, 221 
sodium aluminate, 204 


sodium soap thickening agents, 
209 

valone, 205 

Fuels for flame throwers; see In¬ 
cendiary fuels 

Fuels for incendiary bombs; see 
Incendiary fuels 

Fuzes for bombs; see Bombs, fuzes 

Gardner consistency, 194, 197, 225 
Gardner mobilometer, 194, 201, 218, 

225 

Gasoline gel bombs; see Bombs, 
gasoline gel (oil bomb) 
Geletrol, 204 

Gels, characteristics, 205-206, 217- 

226 

see also Fuels, thickeners 
elastic properties, 217-226 
equations for plastic flow, 222- 
224 

gel formulas, 206-209 
healing time of gels, 224 
physical properties of gels, 207 
relaxation of gels, 217-226 
shear initiation stress, 218 
stringiness of gels, 226 
viscosity coefficient, 218 
viscosity measurements, 218-225 
yield value, definition, 217 
German incendiary bombs, 7 
German structures, bomb tests, 70- 
76, 81-85 

combustibility of German fur¬ 
nishings, 83-85 
industrial targets, 81 
M69 bomb, fire starting effi¬ 
ciency, 19 

Gilbert and Barker Mfg. Co., mech¬ 
anized flame throwers, 103 
GP bomb (General Purpose), 87 
Grease gun viscosimeter, 218, 220 
Grove air pressure regulator, 123 

H2, sabotage incendiary, 47 
Harshaw Chemical Co., fuel thick¬ 
eners, 205 

Harvard candle (fire starter), 47 
Harvard University; development 
of napalm, 192 
E3 bomb, 40 
E20 bomb, 41 
sabotage incendiaries, 47 
tests on incendiary materials, 56 
High-pressure capillary viscosime¬ 
ter, 218 

Huntsville Arsenal, bomb tests on 
farm buildings, 69 


1-3 flame thrower, 124-126 
Igniters for bombs, 45 
Ignition of wood, factors govern¬ 
ing; see Wood ignition 
IM (isobutyl methacrylate), 10, 
192 

IM-II gel, 225 
Imo pump, 144 

Imperial Paper and Color Corp., 
napalm manufacturer, 193, 197 
Incendiaries, sabotage, 46-49 
comparison of FM and H2; 48 
pocket size, 46-49 
Incendiary attacks, analysis; night 
missions, 91 

on Japanese cities, 20, 90-94 
Incendiary bombs; see Bombs 
Incendiary fuels; aluminum com¬ 
pounds, 212 
amines, 200 

bismuth compounds, 212 
cellulose bodied, 13, 209 
containing heavy oil, 201 
diethyl zinc, 212 
IM filling, 13 

napalm thickened gasoline, 192- 
205 

nitrated arsenic and lead deriva¬ 
tives, 212 

organometallic compounds, 212- 
213 

phosphorus-phosphorus sesqui- 
sulfide, 213-214 
set time, 195-197 
S.O.D. formula, 13 
thickening agents, 192 
triethyl boron, 212 
xylenol, 199-200 

Incendiary gels; see also Fuels, 
thickeners; Gels, character¬ 
istics 

formulas, 207 
Incendiary leaf, 50 
Ml; 50 
M2; 51 

Incendiary tests; see Bombs, tests 
Iowa University, E19-19 flame 
thrower, 135 

Isobutyl methacrylate interpolymer 
formulas, 207 

Isobutyl methacrylate polymer, 192, 
207 

Japanese cities, bombing, 13, 21, 
90-94 

accuracy of bombing raids, 91-94 
description of raids, 90-94 
incendiary attacks, summary, 20- 
21 




INDEX 


256 




M19 bomb cluster, 13 
M69, efficiency, 92 
minimum effective bomb load, 92 
types of munitions used, 90 
Japanese structures, bomb tests, 
19, 51, 75-86 
airborne bomb tests, 75 
combustibility of Japanese fur¬ 
nishings, 83-85 
effect of M69 bomb, 19, 79 
flame gun attacks, 116 
industrial targets, 81 
moisture content of Japanese 
wood, 79, 83-84 

Javelins for bomb clusters, 37 
Jefferson Proving Ground, bomb 
comparison tests, 70 
Jet bombs, 7 
Jet force on a target, 187 
Jeweler’s lathe viscosimeter, 218 

Kellogg Co., M.W. flame thrower, 
113, 117 

Kilgore Manufacturing Co., metha¬ 
crylate gels, 209 

LCM boats, flame thrower installa¬ 
tions, 113 

LCVP boats, flame thrower instal¬ 
lations, 113 

Lima Locomotive Works, E14-7R2 
flame thrower, 117 
Little, Arthur D., Inc., 156-165 
anti-personnel tank projector, 
156-158 

E16 all-ways fuze, 49 
flame thrower countermeasures, 
159-161 

physiological effects of flame, 
158, 159 

LVT-Al amphibious tank, flame 
thrower, 116 

Ml bomb fuze, 11 
Ml Are starter, 47 
Ml incendiary leaf, 50-51 
M2 incendiary leaf, 51 
M2-2 flame thrower, 100 
M4 adapter for bomb clusters, 13 
M4 tank, flame thrower unit, 109 
M4A1 tank, flame thrower, 128, 

120-122, 132 

M4A3 tank, flame thrower, 120- 

122, 135-143 

M5 igniter for M76 bomb, 46 

M5A1 tank, flame throwers for, 

110, 122, 126 

M7 adapter for bomb clusters, 13 


M9 igniter for M47 bomb, 45 
M12 bomb burster, 45 
M12 bomb cluster, 13 
M13 bomb cluster, 13 
M13 burster for M47 bomb, 45 
M14 burster for M76 bomb, 46 
M19 (E46) bomb cluster, 13, 15, 30 
M21 (E74) bomb cluster, 23 
M23 adapter for bomb clusters, 13 
M29 primer for E16 fuze, 49 
M46 bomb, 41 

M47 bomb; bombing industrial tar¬ 
gets, 80-82 
fillings, 199, 207-208 
fuel, 192 

fuel thickeners, 207 
igniter and burster, 44-46 
motion pictures of burst, 44 
probability of starting fire, 88 
M50 bomb; effect on farm build¬ 
ings, 69 

effect on Japanese structures, 75 
German houses, 70-76 
penetrating power, 69 
probability of causing fire, 65, 89 
tests on industrial targets, 63, 
80-82 

thermite mixtures, 52 
M52 bomb, 51-52, 69 
effect on Japanese houses, 51 
M54 bomb, 69 

M69 bomb, design details; bomb 
clusters, 13, 27-33 
cloth streamer tail, 16 
ejection-ignition charge, 12 
fillings, 10, 12, 199, 206 
fuel, 192 
fuzes, 10, 11, 49 
impact diaphragm assembly, 10, 
12 

nose cup, 9, 11 
principal components, 10-11 
tail retainer assembly, 10 
M69 bomb, effectiveness, 19-21, 60- 
63, 70-82, 92-94 

attacks on Japanese cities, 92-94 
fire-fighting tests, 76 
fii'e starting efficiency, 19, 64-65 
mortar gun tests, 55 
tests on attic structures, 60 
tests on German houses, 19, 70-76 
tests on industrial targets, 62-63 
tests on Japanese structures, 19, 
75-86 

M69 bomb, performance factors; 
ballistic characteristics, 18 
dispersion patterns, 18 
flight stability, 18 


ignition during fall, 14 
penetrating power, 19, 68, 69 
M69X bomb, 21-27, 68-72 
anti-personnel use, 21, 26 
bomb clusters, 23 
fragmentation, 26 
modifications, 21 
moisture proof characteristics, 
26 

performance, 23 
tests on German houses, 70-72 
M74 bomb, 62-65, 79-82 
mortar gun tests, 55 
penetrating power, 69 
probability of causing fire, 63, 65 
tests on industrial targets, 63- 
64, 80, 81 

tests on Japanese room, 77 
M76 bomb; M5 igniter, 46 
MacMichael viscosimeter, 186, 218 
Magnesium incendiary bombs; see 
Bombs, magnesium 
Mark I flame thrower, 112-116, 198 
attacks on Japanese positions, 
116 

E7 flame gun, 113-115 
fuel system, 113-115 
ignition system, 115 
installation, 112, 116 
performance, 116 
propellant system, 113 
range, 116 
tests, 116 

Mark I fuel mixer, 155, 156 
mixing process, 155 
performance, 155, 156 
Massachusetts Institute of Tech¬ 
nology, 103, 132, 166 
E13R1-13R2 flame thrower, 132 
flame throwers, mechanized, 103 
nozzle design for flame throwers, 
166 

Medium tanks, flame thi’owers, 109, 
120-122, 142 

Metalex (aluminum soap), 204 
Methacrylate thickening agents, 
104, 205-206 
formulas for, 207 
isobutyl methacrylate polymer, 
207 

preparation of gels, 208-209 
use in bomb fillings, 205-207 
Methacrylic acid, 36 
Methylaluminum sesquichloride, 212 
Mobilometer, Gardner, 201, 218, 
225 

Moisture proofing M69X bomb, 26 
Monododecylamine, 205 


liHClASSIFIED 






Monsanto Chemical Co., plastic 
bombs, 42 

Morgan Construction Co., E13-13 
flame thrower, 128 
Moyno I’otor pump, 104 
Napalm, 192-205 
for blaze bombs, 198-199 
ground napalm, 199 
healing rate, 204 
incorporation of dehydrating 
agents, 200-201 

incorporation of heavy oils, 201 
infra-red drying equipment, 194 
manufacture, 193-197 
peptized napalm, 199-200 
raw materials, 193 
silica gel, 201 

specifications, 192, 194, 196-197, 
204 

stir time, 197 
temperature effects, 202-203 
use in flame throwers, 198-199 
variability, 194 

viscosimeter for measuring con¬ 
sistency, 201-203 
Napalm gels, 196-197 
National Foam Systems, Inc., fuel 
mixer, 198 

Neo-fat 3R (soap thickener), 192 
Newtonian fluids, 166, 186-191, 202, 
218 

Nitro-aryl arsenic acids, 212 
Nitromethane for incendiaries, 50 
Nozzle design for flame throwei’s, 
166 

Nozzle discharge coefficients, 176 
NP ; see Napalm 

Nuodex Products Co., napalm de¬ 
velopment, 192 

Oedema, 159 

Office of Strategic Services, sabo¬ 
tage incendiaries, 46 
Oil incendiary bombs; see Bombs, 
gasoline gel (oil bomb) 
Oleopalm (soap thickener), 192 
One-shot flame throwers, 96, 101, 
105 

Organometallic compounds, 212- 
213 

OSS time-delay pencil, 47 

Palmene (soap thickener), 192 
Pendulum test for bombs, 53 
Peptized fuels, 199-201 
amines, 200 

super-peptized fuels, 200 
xylenol, 199 

Phosphorus igniter for bombs, 44 


Phosphorus-phosphorus sesquisul- 
fide, 156, 213-214 
effect on various materials, 214 
liquid EWP, 213-214 
self-ignition, 214 
thickened EWP, 214-215 
Pipe flow viscosimeter, 218, 220 
Plastic bombs, 42 
Pocket size incendiaries, 46 
Polyisobutyl methacrylate polymer, 
36 

Polyisobutylene, 208 
Polystyrene, 214 
Polyvinyl ethers, 208 
Portable flame throwers; see Flame 
throwers, portable 
Primacord bursters, 28 
Primer caps for incendiary bomb 
M69; 11 

Probability of fire starting with 
incendiaries, 64, 88-89 
Pseudoplasticity, 221, 226 
Pumps for flame throwers, 104, 
143, 201 

Blackmer pump, 201 
Imo pump, 144 
Moyno rotor pump, 104 
Sundstrom pump, 104 
Pyroxylin for incendiaries, 51 

Q mechanized flame thrower, 103 

Resinox plastic, 43 
Reynolds number in flame thrower 
jets, 184, 191 
Ricinoleic acid, 205 
Ronson Lighter flame thrower, 103 
Rosin-Fehling correlation, 184 

Sabotage incendiaries, 46-47 
FM; 48 
H2; 47 

Ml fire starter, 47 
SDO (synthetic drying oil), 48 
Seaming compound, vinylite, 12 
Shell Development Co.; Model 1-3 
flame thrower, 124 
nozzles, high-pressure hydraulic, 
166 

tests on flame throwers, 105 
Ship conning tower, protection 
against suicide plane attack, 
161-165 

Snapshot model flame thrower, 96 
S.O.D. formula, 12, 13 
Sodium aluminate, 205 
Standard Oil Development Co.; 
analysis of attacks on Jap¬ 
anese targets, 85 


ball viscosimeter, 201 
bomb tests on attic structures, 
59-60 

bomb tests on typical German 
constructions, 70 
E2 flame thrower, 95-100 
E7-7 flame thrower, 110-112 
E9 flame thrower, 126 
E18 aimable cluster, 28 
E20-20 flame thrower, 140 
flame thrower servicing unit, 
147, 148 

MlAl flame thrower, 96 
M69 bomb, 8-21, 58 
M69X bomb, 21-26 
nozzle design for flame throwers, 
167 

Q mechanized flame thrower, 103 
test on penetration of bombs, 69 
tests on incendiaries, 53, 58 
Stormer viscosimeter, 218 
Suicide plane attacks, countermeas¬ 
ures, 161-165 
Sundstrom pump, 104 

Tanks with flame throwers; instal¬ 
lation of flame throwers, 
109-112, 116 

LVT-Al amphibious tank, 116 
M4; 120, 128, 132, 135-139 
M5; 122-124, 126 

Targets for bomb tests; see Bombs, 
tests 

Tests on incendiaries; see Bombs, 
tests 

Texas Co.; E9 oil bomb, 33-40 
fortified fuel for E9 bomb, 210 
test on incendiary fuels, 67 
Thermate bombs, 42 
Thermite bombs, 52 
Thixotropy, 225 
Tokyo raids, 91 

Trailer model flame thrower, 110 
Triethanolamine, 205 

Valone (gasoline thickener), 205 
Venturi effect, 167 
Vinylite seaming compound, 12 
Viscosimeters; ball viscosimeter, 
201 

C-ration can viscosimeter, 202 
Clark-Hodsman, 218, 219 
grease gun, 218 
high-pressure capillary, 218 
jeweler’s lathe, 218 
MacMichael, 186, 218 
measurement of napalm consist¬ 
ency, 201-202 







mobilonieter, 218 
pipe flow, 218 
Stormer (modified), 218 
Vistanex (polyisobutylene), 208 
Water fog curtains for fire ex¬ 
tinguishment, 160 


“Water hammer” effect in flame wood species, 84 

guns, 172 wood thickness, 84 

Wood ignition, 82-85 

moisture content, 83-84 Xylenol, 155, 198, 199, 202 

endothermic decomposition, 82 

required radiation density, 82 Zinc diethyl, 212 













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